There is not as much demand for castles as there used to be, and most of Europe is filled with old fortifications gone to seed. The castle built by the Knights of St. John in the Greek city of Halicarnassus was named for St. Peter (Petronius) and gave its name in time to the city of Bodrum. Bodrum castle was the stealth bomber or aircraft carrier of its day, a striking military innovation that combined French and English castle technology. Those who worked on the castle were guaranteed a place in heaven by the pope, and they earned it by building thick walls of green volcanic stone, supported by marble quarried from the ruins of the mausoleum that had previously occupied the site. Fourteen cisterns in the rock under the castle collected water for use during sieges, and there were 7 towers and 7 gates, each one the responsibility of one of the langues(tongues) or subunits of the order under the command of its own Bailiff. The walls around each of the gates twisted and turned, so that attackers could find no refuge from the projectiles that rained down on them from above, and a wall of carved reliefs on the castle parapet kept out missiles shot by the attackers. A three-story English tower is connected to the castle by a drawbridge on one side but otherwise presents a high rampart.
The castle survived multiple sieges until it was taken by Suleiman the Magnificent in 1522, and was thereafter used in much the same way by the Ottomans, except that the vaulted Gothic chapel built by the Spanish Knights of Malta was converted into a mosque. With the decline of the Ottoman Empire the castle fell into disuse, but in 1962 it was turned into a Museum of Underwater Archeology, to house the relics excavated from ancient shipwrecks in the Aegean Sea. Most of its collection dates from underwater excavations after 1960. The former chapel houses an exhibition of vases and amphoras from the the Bronze Age of 2500 BCE and the Mycenaean period about 1200 years later. The Italian tower houses a multi-century collection of coins and jewelry. The museum also contains one of the largest collections of ancient glass, and a garden exemplifying almost every Mediterranean plant species. At 600 years of age, Bodrum Castle is playing a new role in a new millenium.