Presidio

A presidio (from the Spanish, presidir, meaning "to preside" or "to oversee") is a fortified base established by the Spanish in areas under their control or influence. The term comes from Latin presidium and its means fortress.

The fortresses were built to protect against pirates, hostile Native Americans, and colonists from enemy nations. Later in western North America, with independence, the Mexicans garrisoned the Spanish presidios on the northern frontier and followed the same pattern in unsettled frontier regions like the Presidio de Sonoma, at Sonoma, California and the Presidio de Calabasas, in Arizona.