The Chapel of the Castle was constructed (using materials from ancient Hellenistic constructions; green stones inside are from the Mausoleum) by the Knights of St. John and is claimed to be the most beautiful building in the castle. It was probably first built in 1406 and was then reconstructed in the Gothic style by the Spanish Knights in 1519-20. After the castle was surrendered to the Turks in 1522 a minaret was added and the building became a mosque. The famous Turkish travel writer Evliya Çelebi wrote, after a visit in 1671, it was called the Süleymaniye Mosque. The minaret was destroyed in WW I when the French shelled the castle on May 26 1515. It was rebuilt in 1997.
Inside the chapel a ship from the 7th century AD is on display.