The Crusader castle was built by the Knights of St. John between 1402 and 1409. After being defeated in Symrna, the Knights came to Halikarnassos and began the construction of the castle. Unknowingly, they used many stones from the great tomb of Mausolus. Today on the walls of the castle you can see lots of stones from Mausoleum, one of the seven wonders of the ancient world. The Mausoleum. . . Mausolus was the ruler of the Caria Kingdom between 377 and 353 BC, he made Halikarnassos its capital. Then he enclosed his new capital with a huge wall. He also adorned the city with splendid edifices, the most famous of which was the Mausoleum which he designed as a great Carian shrine dedicated to himself. His sister-wife Artemisia completed it after he died during her own reign. It was so beautiful that it became one of the seven wonders of the ancient world.