El Camino Real (Spanish for The Royal Road, also known as The King's Highway), sometimes associated with Calle Real (within the US state of California), usually refers to the historic 600-mile (965-kilometer) road connecting the 21 Spanish missions in California (formerly Alta California), along with a number of sub-missions, four presidios, and three pueblos, stretching at its southern end from the San Diego area Mission San Diego de Alcalá, all of the way up to the trail's northern terminus at Mission San Francisco Solano in Sonoma, just above San Francisco Bay.