Legend has it that Doña Urraca was locked in the tower of the Palace of Fernán González. It was built in the 10th century and was a defensive building. It has a rectangular floor plan and a pyramid elevation. In the doorway there is a horseshoe arch, which leads to a space with a barrel vault resting on scotia imposts. The tower exterior is smooth and is crowned by aggregate machicolations. It has a hip roof instead of battlements.