The Moat of the Medieval Town of Rhodes

Identity

A Linear Monument, Not a Single Building

The Collachio and the Burgh › a 2,500 m circuit from the Palace to the bastion of St Athanasios

Unlike the buildings documented elsewhere in this series, the Moat of the Medieval Town of Rhodes is not a single structure but a linear archaeological and defensive landscape, developed from an earlier Byzantine fortified nucleus and continually adapted as the town’s defences grew. It possesses what this document calls a ‘triple character’: it is simultaneously an archaeological site, cut some 3–4 m below the level of the ancient Hippodamian streets and preserving ancient drains, conduits and rock-cut features within its bed; a component of the standing fortification monument in its own right, with its own proteichisma, contrascarpa and wall-walk; and a landscaped public park with a distinctive microclimate, created principally during the Italian period of the twentieth century and substantially re-presented since 1995.

Location & extent

Encircles the landward fortifications of the Collachio and the Burgh, from the Palace of the Grand Master in the north, round the western and southern land walls, to the area of the Acandia Gate and the bastion of St Athanasios in the south — a walkable public circuit of roughly 2,500 m within an overall wall enclosure reckoned at about 4 km.

Scale

Part of the wider 350,000 m² (35 ha) monumental complex of the Rhodes fortifications; the moat floor lies some 3–4 m below the level of the ancient streets, with walls documented at up to 12 m in thickness.

Construction history

Byzantine fortified nucleus, continually adapted; progressive medieval widening tied to quarrying, anchored by a document of 20 March 1441 linking moat stone to the construction of the Great Hospital of the Knights; division among the Order’s langues from 1465; Italian-period park designation in 1920; Greek-administration restoration programme 1995–2008 under the March 2001 Master Plan.

Heritage designation

Component of the ‘Medieval City of Rhodes’ UNESCO World Heritage property (inscribed 1988, criteria ii, iv, v); protected under Greek Archaeological Law 3028/2002.

Present use

Public archaeological site, landscaped walkway and open-air theatre, administered by the Ephorate of Antiquities of the Dodecanese, with the Municipality of Rhodes contributing to the upkeep of park areas and visitor amenities.

Defence

The Geometry of a Killing Ground

Moat · proteichisma · contrascarpa · wall-walk › a layered, engineered defensive apparatus

The moat was not a passive ditch — it was the single most engineered part of the entire Rhodes defensive system. Its basic job was to keep an attacker’s siege engines, battering rams and sappers away from the base of the wall, where masonry is most vulnerable and undermining is easiest; but at Rhodes it did far more than simply hold the enemy at a distance. An attacker who got past the counterscarp still had to cross the ditch floor, get past or over the proteichisma, and then scale the main rampart — all while exposed the entire time to fire from the flanking bastions on either side. The Order’s own heritage-narrative material describes the moat as fitted with “countless deadly openings and vents, cannon firing angles with angles cleverly calculated to prohibit any potential enemy approach to the walls”: a geometrically calculated killing zone, not just an obstacle.

The ditch (moat proper)

The excavated void itself, cut some 3–4 m below the level of the ancient streets and kept, along virtually its whole circuit, deliberately dry.

The proteichisma (faussebraye)

A lower outer defensive wall set within the ditch, doubling the number of obstacles an attacker had to cross under fire and giving defenders a manned firing line in its own right.

The contrascarpa

The ditch’s outer retaining face, a sheer rock-cut escarpment on the counterscarp side.

The wall-walk (περíδρομος)

Running along the principal fortifications above; the stretch from the Gate of the Cannons to the Gate of St John has been conserved and opened to visitors.

Why dry, not flooded. A flooded moat is good at one thing — stopping tunnelling, since water floods any mine shaft dug beneath it — but it is a largely passive barrier that nobody fights inside. A dry ditch could be actively fought over, exactly as happened during the 1522 siege when English and German knights held an inner barricade against repeated Ottoman assaults inside the ditch itself. The Hospitallers engineered an opposing slope on the glacis specifically to shed rainwater rather than collect it, which is why the chronicler Caoursin’s contemporary miniatures of the 1480–81 siege record only a single small lagoon, in the moat’s south-eastern stretch near Acandia, rather than a flooded ditch.

Why kept clear of vegetation. The flanking cannon and crossbow positions built into the bastions depended on unobstructed sightlines along the ditch floor; scrub or trees would have created dead ground where an attacker could shelter unseen, and overgrowth supplied the besiegers’ own technique, since cut brushwood was the standard material used to fill ditches with fascines for a rapid assault ramp. Root growth also destabilises masonry and rock-cut joints over time — precisely the damage a 1997 conservation study identified as needing large-scale remedial intervention. Under the Order’s 1465 division of the defences, each langue was responsible not only for defending its stretch of wall and moat but for maintaining it, and keeping a post clear of vegetation and standing water was as much a part of that obligation as repairing stonework.

Government

Nine Posts, One Wall

1465 › Grand Master Zacosta divides the circuit among the Order’s langues

In 1465, Grand Master Pedro Ramon Zacosta divided the newly completed circuit of the defences into battle stations allotted by nationality: each of the Order’s langues, or national Tongues, was assigned a specific stretch of wall and moat, and each Tongue became permanently responsible for both defending and maintaining its own post. This single administrative act is the direct origin of the moat’s sector-by-sector character, documented Post by Post, each still legible today in its sector’s name and treatment — from the austere, cut-rock straight stretch of the Post of England to the shaded, tree-planted rest areas of the Post of Spain and the abundant greenery of the Posts of Italy and St John.

France

Covers the Collachium Gate and the northeast corner of the Palace under the 1465 decree; reassigned in the siege of 1522 to run from the Mole of Naillac to the Gate of Amboise. Tower St Peter, round and bulwarked, protects the military port of Mandraki, its north façade bearing the arms of Pope Pius II and Grand Master Zacosta.

Provence

Runs from St John’s (Koskinou) Gate to the bastion of Grand Master Pierre d’Aubusson, following a course of angles and recesses ideal for flanking fire. A lofty tower fronts St John’s Gate, bearing a relief of St John the Baptist and the arms of Grand Master Antoni Fluvià.

Italy & St John

The stretch at the del Carretto bastion and beyond, marked by abundant greenery and cultural use; it now hosts the Open-Air Theatre ‘Melina Merkouri’.

England

Runs from the bastion of Spain to the Tower of the Virgin under the 1465 decree (defended by the Tongue of Spain in 1522), including the Gate of St Athanasios. An austere, straight stretch of cut rock face, the scene of the bloodiest fighting of the 1522 siege.

Spain

The round Tower of Spain, originally free-standing, bears the arms of Grand Master Pierre d’Aubusson and the date 1489 on its external southern façade. Reassigned to the Tongue of England in 1522; shaded by large trees near the bastion of St Athanasios, this stretch is treated today as a rest and visitor-services area.

Castille

Runs from St Catherine’s Gate to the Gate of St Paul, protecting the coastal area of the city with Porta Marina as a bastion and the towers of Naillac and of the Angels defending the Commercial Harbour.

Italy

The Tower of Italy marks the start of this section, running to St Catherine’s Gate; proved especially vulnerable in the first Ottoman siege of 1480. The round bastion of Grand Master Fabrizio del Carretto, originally one of the city gates, stands within it.

Germany

Runs from St Anthony’s Gate to the Tower of St George, defended by the German Knights after the 1465 division.

Auvergne-Germany & the Bastion of St George

Begins at the bastion of St George, the largest and most developed of the fortification’s bastions, reaching to the Tower of Spain. Its earliest phase dates to Grand Master Antoni Fluvià, whose arms and a relief of St George, alongside those of Pope Martin V, are set in its west façade; in 1496 Grand Master Pierre d’Aubusson blocked up the old gateway to convert it into a strong bastion.

Testimony

An Active Killing Ground, 1480 and 1522

Caoursin’s miniatures · the breach of 4 September 1522 › Ahmed Pasha’s mines

The moat’s significance rests not only on its archaeological and landscape values but on its documented role as an active, and at times particularly bloody, killing ground in both the sieges the Order withstood at Rhodes.

Caoursin’s miniatures, 1480–81

The Order’s own chronicler, Guillaume Caoursin, illustrated the first siege with contemporary miniatures that record only a single small lagoon forming in the moat’s south-eastern stretch, near Acandia — direct visual evidence that the ditch’s engineered drainage was already functioning as intended, keeping the circuit dry and fightable rather than flooded and passive.

Guillaume Caoursin, collected works on the Siege of Rhodes and related events, Ulm: Johann Reger, completed 23 October 1496.

The breach of the bastion of England, 4 September 1522

Two gunpowder mines exploded beneath the bastion of England and brought down twelve metres of wall. The Ottomans assaulted immediately and held the gap; the English and German Knights under Fra’ Nicholas Hussey held an inner barricade and were soon joined by Grand Master de l’Isle Adam. The Knights regrouped, charged the Ottoman position, drove back the enemy and captured their standards — Mustafa Pasha twice more renewed the assault on the damaged bastion, and twice more the English and German brothers drove him back, at a reported cost of over 2,000 Ottoman dead before the position was retaken.

Drawn from the broader historiographical tradition on the 1522 siege, as synthesised in this document’s own account of the Battle Post of England.

Ahmed Pasha’s mines, 1522

As other efforts proved fruitless, the Ottomans turned to undermining the ramparts and blowing them up with mines beneath sustained artillery barrage. The regularity of the detonation points — generally where the walls rest on rock — has led to the suggestion that Ahmed Pasha, an experienced siege engineer, took advantage of the ancient culverts of Hippodamian-Hellenistic Rhodes, lying beneath the medieval city and the moat’s own bed, to drive his mines toward the ramparts.

The ancient sewage pipeline is carved into the limestone and remains visible today at the level of the lower emplacement, where the bastion meets the natural rock, and at the counterscarp, where the rock level is lower.

Discovery

Beneath the Ditch, Since 1995

1441 quarry document · 2000–2008 excavation › the Master Plan of 2001–2002

The moat preserves a direct, precisely dated material link to the construction history of another major Hospitaller monument. A document of 20 March 1441 records an agreement between the Order and Prior Jean Morel, under Grand Master Jean Bonpar de Lastic, by which Morel could obtain stone from ‘the quarry near the vaults of the Tarsanas’ for the construction of the ‘New Hospital’ — the Great Hospital of the Knights, documented separately in this series — plausibly identifiable with quarrying traces still visible today along the moat near the bastion of St George. Since 1995, and with expanded funding from 2000 under the European Union’s 3rd Community Support Framework, the moat has been the subject of a long-running, scientifically rigorous restoration programme coordinated by the 4th Ephorate of Byzantine Antiquities, itself now a significant chapter in the history of Greek monument conservation.

20 March 1441

Agreement permitting Prior Jean Morel to obtain quarry stone near the moat, under Grand Master Jean Bonpar de Lastic, for the construction of the Great Hospital of the Knights.

1920

The Italian administration designates the moat’s peripheral glacis — previously ground that had served, among other things, as Muslim and Jewish cemeteries — as parkland; the cemeteries are removed and the ‘Auvergne garden’ laid out north of the Palace.

1995–2008

A Greek-administration restoration programme, coordinated by the 4th Ephorate of Byzantine Antiquities, opens the moat and its bastions to the public as an organised archaeological and landscaped walk.

March 2001 / September 2002

A Master Plan for the protection, arrangement and enhancement of the fortifications is completed and then approved by the Ministry of Culture, following a unanimous opinion of the Central Archaeological Council, setting the guidelines for all subsequent intervention.

2000–2008

Archaeologists Anna-Maria Kasdagli and Melina Filimonos-Tsopotou lead research at the Post of Auvergne-Germany, opening part of the underground galleries beneath the curtain wall and confirming, by excavation, that this ancient water-supply network communicates with the area of the Hospitaller church.

22 April 2003

The Ministry of Culture approves the Open-Air Theatre ‘Melina Merkouri’, designed by architect K. Manousou-Della, replacing a disruptive metal structure erected in 1983.

Gallery

Photo gallery

Fifteen views › the circuit, its Posts, its heraldry and its modern theatre

Assessment

Significance criteria

Nine-criteria framework › International importance, with a qualified integrity rating

Rarity

A medieval fortification ditch preserved, surveyed and re-presented across its full circuit as a combined archaeological site, standing defensive monument and designed landscape is a rare survival; comparable European town moats are far more often infilled, reduced to a single function, or documented only in fragments. The moat’s 2,500 m of continuous, sector-by-sector legible fortification, spanning multiple langues’ distinct Posts, is itself an unusual degree of completeness.

High

Representativeness

Highly representative of the Hospitaller Order’s defensive engineering as a ‘polygonal system’, continuously adapted from an earlier Byzantine nucleus and divided among the Order’s langues; it complements, rather than duplicates, the governmental, charitable and naval identities of the Order already documented elsewhere in this series at the Palace of the Grand Master, the Great Hospital of the Knights and the Military Harbour (Mandraki).

Exceptional

Aesthetic value

The moat offers a notably favourable microclimate for vegetation and unique views of the fortifications, its character varying deliberately from sector to sector — from the austere, cut-rock straight stretch of the Post of England to the shaded, tree-planted rest areas of the Post of Spain and the greenery of the Posts of Italy and St John — a quality inseparable from the Italian-period park landscaping of the 1920s and its later, sensitive enhancement.

High

Integrity

Varies across the monument’s components. The underlying defensive engineering and much of the moat’s rock-cut and archaeological fabric retains a high degree of authenticity. The designed landscape, by contrast, is substantially a twentieth- and twenty-first-century layer: the Italian-period park of the 1920s and the Open-Air Theatre. Any conservation or interpretive use should distinguish clearly between these medieval/ancient, Italian-period and post-1995 layers.

Moderate–High

Historical value

Outstanding: as physical evidence of the Hospitaller Order’s continuous, centuries-long fortification programme, anchored by the precisely dated 1441 quarry document linking it directly to the construction of the Great Hospital of the Knights; as an archaeological witness to the ancient Hippodamian town beneath and around it; and as the subject, since 1995, of an exemplary and well-documented modern restoration programme in its own right.

Exceptional

Symbolic, spiritual & social value

As both the dividing line and the principal point of connection between the medieval and modern town, the moat carries strong symbolic value as the physical threshold of the Collachio and the Burgh; socially, its public walk and Open-Air Theatre have made it one of the most actively and variously used heritage spaces in Rhodes, combining recreation, cultural performance and archaeological interpretation in a single continuous space.

High

Scientific value

The moat retains substantial, still only partially explored archaeological potential, demonstrated by the confirmed link between the underground galleries at the Post of Auvergne and the area of the Hospitaller church; its exposed geology and quarrying traces give it independent research value, while the Open-Air Theatre’s geosynthetic reinforced embankment is itself a documented case study in sensitive modern intervention within a historic fortification.

High

Interpretive potential

Unusually rich and physically legible: a single, walkable 2,500 m circuit through which visitors can trace the ancient Hippodamian town, the Byzantine defensive nucleus, the Order’s ‘polygonal system’ and its division among the langues, the precisely dated 1441 quarry document, the Italian-period park, and a well-documented sequence of modern architects, archaeologists and engineers — all within a space that remains in active public and cultural use rather than behind museum walls.

Exceptional

Importance level

Rests on the moat’s unique combination, within a single continuous space, of archaeological site, standing fortification monument and designed landscape; its role, alongside the Palace of the Grand Master, the Great Hospital of the Knights and the Military Harbour of the Knights, as an integral component of the Outstanding Universal Value of the UNESCO-inscribed Medieval City of Rhodes under criteria (ii), (iv) and (v); and its status as the subject of an exemplary, long-running and scientifically rigorous restoration programme.

International

Statement of significance

“The moat wasn’t a passive ditch — it was the single most engineered part of the entire Rhodes defensive system.” (This document’s own characterisation of the moat’s engineered function, drawn from its account of the moat’s layered defensive apparatus.)

A 2,500 m walking circuit within a 4 km overall enclosure, with walls up to 12 m thick, the Moat of the Medieval Town of Rhodes is a monument of international significance. A rare and substantially complete example of a medieval fortification ditch whose sector-by-sector division among the Order’s langues under Grand Master Zacosta’s 1465 reorganisation, it deserves its reputation as part of one of the strongest fortress systems in the Christian world. Its documented role as an active, and at times particularly bloody, killing ground in the sieges of 1480 and 1522 stands alongside its later archaeological and landscape values; all are conserved and interpreted today across its full circuit as archaeological site, standing monument and designed landscape at once. Today the moat remains an integral component, alongside the Palace of the Grand Master, the Great Hospital of the Knights and the Military Harbour of the Knights (Mandraki), already documented in this series, of the Outstanding Universal Value of the UNESCO-inscribed Medieval City of Rhodes under criteria (ii: interchange of human values over time), (iv: outstanding example of human creation) and (v: human settlement/use representative of a culture or human-environment interaction), and is offered to the public via open access.

National

ΥΑ 23084/737/25-8-1948 — ΦΕΚ 10/23-9-1948, the Ministerial Decision declaring the monuments of the Medieval Town of Rhodes, including the moat and the fortification complex, protected under Greek Archaeological Law; subsequently confirmed under Law 3028/2002 on the Protection of Antiquities and Cultural Heritage in General.

UNESCO

Medieval City of Rhodes (ref. 493), inscribed 1988, criteria (ii), (iv) and (v). The moat is a defining component of the fortified circuit cited in the property’s Statement of Outstanding Universal Value, encircling and directly linking the Palace of the Grand Master, the Great Hospital of the Knights and the Military Harbour of the Knights (Mandraki).

References

Caoursin, Guillaume (Guillelmus Caoursin). [Collected works on the Siege of Rhodes, the earthquake of 1481, the death of Mehmed II, the affair of Prince Cem/Zizim, the treaty with Bayezid II, the relic of the Hand of St John the Baptist, and an oration to Pope Innocent VIII]. Ulm: Johann Reger, completed 23 October 1496.
Gabriel, Albert. La Cité De Rhodes, 1310–1522. Paris: E. de Boccard, 1921.
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Hellenic Government Gazette (ΦΕΚ). Ministerial Decision 23084/737 (25 August 1948), ΦΕΚ 10 (23 September 1948), protection of the monuments of the Medieval Town of Rhodes; Law 3028/2002 on the Protection of Antiquities and Cultural Heritage in General.
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