View of the Castillo de Atienza in Guadalajara province, Castilla-La Mancha, Spain.
The Castillo de Penafiel is located in Valladolid province in Castilla y Leon, central Spain.
The Castillo de San Marcos is the oldest masonry fort in the United States. Located in St. Augustine, Florida, it dates to the late 1700s.
The Alcazar is a 8th century castle/palace located in Segovia, Spain. Originally built by the moors. and later modified by the Spanish kings.