is 1,008 (including 21 on Gyali), although in summer it is augmented by many tourists as well as expatriate Nisyrians who visit the island for their vacations. Tourism is not so heavily developed as on other Greek islands. Deposits of perlite and pumice on Gyali provide much of the wealth of the island. The island used to be self-sufficient, and many crops were grown on its terraced slopes. Today, though, they are cultivated on a smaller scale. History According to Greek mythology, the island was formed when Poseidon cut off a part of Kos and threw it onto the giant Polybotes to stop him from escaping. The ancient name of the Nisyros was Porphyris. Ancient walls, dating from the 5th century BC, part of the acropolis of the island, are found near Mandraki. It was apparently also a source of millstones used in some of the earliest watermills, being referred to by epigrammatist Antipater of Thessalonica in the 1st century BC. The island is mentioned by Homer in the Iliad. In Roman times it became part of the Insulae province. Between X-XI centuries, Genoese captains and adventurers who had a private fleet organized in clans united by family ties, exercised sovereignty and maritime control on behalf of the Byzantines, and these clans in exchange for the protection of the seas were given a concession to exploit raw materials, rights of trade and collection of customs duties. The Knights Hospitaller in 1315 were allowed to settle on the island upon payment of rent to Genoese government ruled by the Vignolo family, and they built the crusader castle. In the following centuries there were clashes with Saracens and Venetians crusaders, and with uncertain outcomes the island passed to Ottomans in 1566; then passed almost 4 centuries later from the Ottomans to the Italians in 1911 during the Italo-Turkish War, along with the rest of the Dodecanese islands. It finally was annexed to the Greek Kingdom after the Second World War, in 1947. Christianity The patron saint of the island is Saint Nikitas. Many Orthodox Christian churches are found on the island, as well as four monasteries which are not inhabited by monks today, although various celebrations take place in them. The largest monastery is the one of Panagia Spiliani (Blessed Virgin Mary of the cave) at Mandraki. It is built beside the medieval castle erected by the Knights Hospitaller. Diocese of Nisyrus