Bodrum Castle Bodrum Castle ( ) , located in southwest Turkey in the city of Bodrum ( ) , was built by the Knights Hospitaller starting in 1402 as the Castle of St . Peter or " Petronium " . History . Confronted with the invasion of Seljuk Turks , the Knights Hospitaller , headquartered on the island of Rhodes , needed another stronghold on the mainland . Grand Master Philibert de Naillac ( 1396 – 1421 ) found a suitable site across the island of Kos , where there was already a castle of the Order . This location had been already the site of a fortification in Doric times ( 1110 BC ) and of a small Seljuk castle in the 11th century . The same promontory was also the probable site of the palace of Mausolos , the famous king of Caria . The construction of the castle began in 1404 under the German knight - architect Heinrich Schlegelholt . Construction workers were guaranteed a reservation in Heaven by a papal decree of 1409 . They used squared green volcanic stone , marble columns and reliefs from the nearby Mausoleum of Maussollos to fortify the castle . The first walls were completed in 1437 . The chapel was among the first completed inner structures ( probably 1406 ) . It consists of a vaulted nave and an apse . The chapel was reconstructed in Gothic style by Spanish Knights in 1519 - 1520 . Their names can be found on two cornerstones of the façade . Fourteen cisterns for collecting rainwater were excavated in the rocks under the castle . Each tongue of the Order had its own tower , each in his own style . Each tongue , each headed by a bailli , was responsible for the maintenance and defence of a specific portion of the fortress and responsible for manning it with sufficient numbers of knights and soldiers . There were seven gates leading to the inner part of the fortress . The architect applied the latest in castle design : the passages leading to these gates were full of twists and turns . Eventual assailants could not find cover against the arrows , stones or heated projectiles they had to confront . The Knights had placed above the gates and on the walls hundreds of painted coats of arms and carved reliefs . There remain now 249 separate designs : those of grand masters , castle commandants , countries , personal coat of arms of knights and religious figures . The construction of the three - storied English tower was finished in 1413 . One door opens to the north , to the inner part of the castle ; The other door leads to the western rampart . One could only access this tower via a drawbridge . The western façade shows an antique carved relief of a lion . Because of this relief , the tower was also called " the Lion Tower " . Above this lion , one can see the coat of arms of king Henry IV of England . For over a century St . Peter ' s Castle remained the second most important castle of the Order . It served as a refuge for all Christians in Asia Minor . The castle came under attack with the rise of the Ottoman Empire , first after the fall of Constantinople in 1453 and again in 1480 by sultan Mehmed II . The attacks were repelled by the Knights . In 1482 , Prince Cem Sultan , son of sultan Mehmed II and brother of sultan Bayezid II , sought refuge in the castle , after a failure in raising a revolt against his brother . When the Knights decided to fortify the castle in 1494 , they used again stones of the Mausoleum . The walls facing the mainland were thickened as to withstand the increasing destructive power of cannons . The walls facing the sea were less thick , since the Order had little to fear from a sea attack due to their powerful naval fleet . Grand Master Fabrizio Del Carretto ( 1513 – 21 ) built a round bastion to strengthen the land side of the fortress . Sir Thomas Docwra was captain of the castle in 1499 . 16th century . Between 1505 and 1507 the few sculptures from the mausoleum , that hadn ' t been smashed and burnt for lime , were integrated into the castle for decoration . These included twelve slabs of the Amazonomachy ( combat between Amazons and Greeks ) and a single block of the Centauromachy , a few standing lions and one running leopard . When faced by attack from Sultan Suleiman , Philippe Villiers de L ' Isle - Adam , the Grand Master of the Knights Hospitallers ordered the Castle to be strengthened again . Much of the remaining portions of the mausoleum were broken up and used as building material to fortify the castle . By 1522 almost every block of the mausoleum had been removed . In June 1522 the sultan attacked the Order ' s headquarters in Rhodes from the Bay of Marmaris with 200 , 000 soldiers . The castle of Rhodes fell in December 1522 . The terms of surrender included the handing over of the Knights ' fortresses in Kos and St Peter ' s Castle in Bodrum . After the surrender , the chapel was turned into a mosque and a minaret was added . This mosque was called the " Süleymaniye Camii " , as attested by a traveler Evliya Chelebi , who visited Bodrum in 1671 . The minaret was destroyed on 26 May 1915 by rounds fired by a French warship during the World War I . It was reconstructed in its original shape in 1997 . 19th century . In 1846 Lord Stratford Canning , the British Ambassador to Constantinople obtained permission to take twelve marble reliefs , showing a combat between Greeks and Amazons . Sir Charles Newton , a member of the staff of the British Museum , conducted excavations and removed a number of stone lions and one leopard in 1856 . Presently , these are all to be found at the British Museum . In later years , the castle has been used for different purposes . It was used as a military base by the Turkish army during the Greek Revolt in 1824 . In the 19th century the chapel was converted into a mosque and a minaret was added . At the same time a hamam ( public bath ) was installed in the castle . In 1895 the castle was turned into a prison . During World War I , the castle was fired upon by a French warship , toppling the minaret and damaging several towers . After the war , the Italians stationed a garrison in the castle , but withdrew in 1921 when Mustafa Kemal Atatürk came to power . Afterwards the castle stood empty for 40 years . Museum of Underwater Archaeology . In 1962 the Turkish Government decided to turn the castle into a museum for the underwater discoveries of ancient shipwrecks in the Aegean Sea . This has become the Bodrum Museum of Underwater Archaeology , with a collection of amphora s , ancient glass , bronze , clay , iron items . It is the biggest of its kind devoted to underwater archaeology . Most of its collection dates from underwater excavations after 1960 . These excavations were performed on several shipwrecks : The former chapel houses an exhibition of vases and amphoras form the Mycenaean age ( 14th to 12th centuries BC ) and findings from the Bronze Age ( around 2500 BC ) . The commercial amphoras give a historical overview of the development of amphoras and their varied uses . The Italian Tower houses in the Coin and Jewelry Hall a collection spanning many centuries . Another exhibition room is devoted exclusively to the tomb of a Carian princess , who died between 360 and 325 BC . The collection of ancient glass objects is one of the four biggest ancient glass collections in the world . Two ancient shipwrecks have been reconstructed : the Fatımi ship , sunk in 1077 AD , and the large Uluburun Shipwreck from the 14th century BC . The garden inside the castle is a collection of almost every plant and tree of the Mediterranean region , including the myrtle , and the plane tree .