Bellver Castle, located in Palma de Mallorca, Spain, is a unique Gothic-style castle built in the 14th century for King James II of Majorca. It stands out as one of the few circular castles in Europe, with a circular floor plan and round towers attached. Originally a royal residence, it later served as a military prison and now houses the city's History Museum. With its distinctive circular shape and historical significance, Bellver Castle is a popular tourist attraction on the island of Majorca.