Castle of the Knights of Saint John

The fortress at the mouth of Kos harbour is known locally as Neratzia, the bitter orange tree, after the groves that once grew inside its walls. Guidebooks list it as the Castle of the Knights of Saint John. Boats still pass directly beneath its seaward wall on the way to the town quay, which is how it was meant to be seen.

Historical Background

The Knights on Kos

The Knights of St John of Jerusalem, based on Rhodes from 1309, held Kos from 1314 until 1522. Kos was the northern outpost of their small island state, and the Anatolian coast lies just across a narrow strait, so the fortress was built to watch a frontier rather than to impress anyone. Its garrison worked in concert with the Knights' other Dodecanese strongholds, including the inland castle at Antimachia and the fortress at Bodrum on the mainland opposite.

Building the Castle

Work on the castle as it stands began in 1436 and finished in 1514. The inner enclosure is older than that programme and appears to pre-date the end of the 14th century; the oldest surviving structure is the round tower to the left of the connecting bridge, which carries the coats of arms of Grand Masters de Lastic (1437-1454) and de Milly (1454-1461). The outer enclosure was begun around 1495 by Grand Master d'Aubusson, continued under d'Amboise and completed by del Carretto in 1514. Its heavy bastions, battlements and gun ports belong to a later kind of warfare than the tall towers behind them: the outer ring was designed to absorb cannon fire and return it.

The Ottoman Attack of 1457

On 3 June 1457 an Ottoman fleet of 156 ships landed some 16,000 men on Kos. The decisive fighting took place not at the harbour fortress but inland at Antimachia, the castle on the plateau in the centre of the island, where fifteen knights and around 300 mostly unarmed people held out for 23 days. The Ottomans withdrew on 26 June, having lost more than a thousand men, and the island stayed in the Knights' hands. Kos was never stormed. When Rhodes capitulated at the end of 1522, the Knights surrendered Kos under the terms of that agreement and sailed away the following year.

Architecture and What to Look For

The castle is, in large part, the ancient city rebuilt. The Knights quarried marble, granite and inscribed blocks from the ruins of ancient Kos and from the Asklepieion, and the reused pieces are visible all over the structure rather than hidden in the core.

• A Hellenistic frieze carved with masks and garlands sits above the central gate, several centuries older than the wall holding it.
• Granite columns taken from an early Christian basilica were laid above the entrance roofs.
• The Carmadino gate is framed by oblique basalt columns, another salvaged set.
• Blazons of the grand masters are set into the curtain walls and towers; read together they date the building phases as clearly as a written record.

The plan is two concentric fortified enclosures separated by a moat, now dry. The inner one has a round tower at each corner; the outer one carries the bastions and gun emplacements added in the decades before 1514.

Visiting the Castle

• The entrance is at Platia Platanou, reached by the arched stone bridge over the old moat from the palm-lined Finikon street. The Tree of Hippocrates and the Gazi Hassan Mosque stand at the same end of the bridge.
• From the top there is a full circle of view: the harbour below, the roofs of the old town, and the sea running east towards the Turkish coast.
• Parts of the castle have been closed for restoration in recent years and access has sometimes been partial, so it is worth checking opening status before making the walk a fixed point in the day.

Neratzia is one of the few Greek island castles that reads better from the water than from the road, since its seaward face was built to be judged by approaching ships. Entering the harbour, the whole outer enclosure lines up in a single view, and many visitors combine a day of sightseeing with a private gulet charter from Kos for exactly that reason.