Bluebeards Castle Hotel is located on a hilltop over viewing the water about 3 miles from the airport. Legend.It is believed that Bluebeard built this castle for his love, Mercedita. When he found out she had cheated on him, he killed her and left never to return. It was a watch tower that assisted the Fort Christian fortress built by the Danish in the 1670s. Fort Christian is one of the oldest buildings on St. Thomas.