View of a gate; The Knights Hospitaller, however, who had captured Rhodes from the Greeks in 1309, retained the tripartite division of the Byzantine settlement and improved its fortifications. The citadel in the north-west corner was transformed into the Grand Master's Palace. The Hospitallers also improved the defences of the commercial harbour (the emborio) with the addition of walls, towers and a chain blocking the entrance. A bay to the north, known as Mandraki, sheltered the arsenal. Outside Rhodes town the Hospitallers refortified ancient citadels and built castles and towers around the island, on rocky hilltops on or near the coast (e.g. Archangelos, Feraklos, Lindos, Apolakkia, Monolithos). Stretches of castle and tower walls still ...