San Jeronimo Castle, Spanish colonial fort in Portobelo District, Panama

San Jerónimo Castle, also called Fuerte de San Jerónimo de Portobelo, is a military fortification on the Caribbean coast of Panama. Its stonework shows the military architecture of the 17th and 18th centuries, built as part of Spain's defensive system for transatlantic trade. The castle and the historic ruins of Portobelo District were declared a national historic monument by Law 68 of 1941.

The fort was built between 1596 and 1779 and served to protect Spanish trade routes from pirate attacks. It played an important role in securing the transport of South American goods to Europe.

The fort displays construction styles from different periods shaped by various European powers. Visitors can still see today how fortification techniques evolved over time.

The walls and walkways are reinforced with restored bricks and can be walked on. The path is generally accessible but requires sturdy footwear due to uneven surfaces.

The fort was declared a national historic monument by Law 68 of 1941, together with the historic ruins of Portobelo District. Earlier, Law 61 of 1908 had already allocated funds for its conservation.