Fort Guijarros (Spanish "Castillo de Guijarros" ) was a Spanish fort in what is now San Diego, California, USA. The name means "Fort Cobblestones" in English. It was built in 1797 on Ballast Point as the first defensive fortifications for San Diego Bay. It was involved in the Battle of San Diego, a naval battle between the fort and an American trading vessel. The site is registered as California Historical Landmark #69.