The Fort of San Diego (Spanish: Fuerte de San Diego), formerly also known as the Fort of San Carlos (Spanish: Fuerte de San Carlos) is a star fort in Acapulco, Guerrero, Mexico. It was built by the Spanish Empire, and it was one of the most important Spanish fortifications along the Pacific coast. The fort was first built in the 17th century, but was completely rebuilt in the 18th century. Today, it is an important landmark in Acapulco, and it is open to the public as the Acapulco Historic Museum (Spanish: Museo Histórico de Acapulco).