Mission Basilica San Diego de Alcalá was the first Franciscan mission in The Californias, a province of New Spain. Located in present-day San Diego, California, it was founded on July 16, 1769, by Spanish friar Junípero Serra in an area long inhabited by the Kumeyaay people. The mission and the surrounding area were named for the Catholic Didacus of Alcalá, a Spaniard more commonly known as San Diego.
The mission was the site of the first Christian burial in Alta California. San Diego is also generally regarded as the site of the region's first public execution, in 1778. Father Luis Jayme, California's first Christian martyr, lies entombed beneath the chancel floor. The current church, built in the early 19th century, is the fifth to stand on this location. The mission site is a National Historic Landmark.
The former Spanish settlement at the Kumeyaay Nipawai lies within that area occupied during the late Paleoindian period and continuing on into the present day by the Native society commonly known as the Diegueño; the name denotes those people who were ministered by the padres at Mission San Diego de Alcalá.
Relatively, much is known about the native inhabitants in recent centuries, thanks in part to the efforts of Juan Rodríguez Cabrillo, who explored the coast in the service of Spain. He documented his observations of life in the coastal villages he encountered along the Southern California coast in October 1542.
Cabrillo was the first European to set foot in what is now the state of California and the first to encounter San Diego Bay. On the evening of September 28, 1542, the ships San Salvador and Victoria sailed into the harbor, whereupon Cabrillo christened it "San Miguel." During that expedition a landing party went ashore and briefly interacted with a small group of natives. Some sixty years later another Spanish explorer, Sebastián Vizcaíno, made landfall some ten miles from the present Mission site.
Under Vizcaíno's command the San Diego, Santo Tomás, and frigate Tres Reyes dropped anchor on November 10, 1602, and the port was renamed "San Diego de Alcalá." It would be another 167 years before the Spanish returned to San Diego.
Ever since the voyages of Christopher Columbus, the Kingdom of Spain sought to establish missions to convert the pagans in Nueva España ("New Spain") to Roman Catholicism to save souls and to facilitate colonization of these lands. However, it was not until 1741—the time of the Vitus Bering expedition, when the territorial ambitions of Tsarist Russia towards North America became known—that King Philip V felt such installations were necessary in Upper California.
In 1769, Visitador General José de Gálvez sent the expedition of Junípero Serra and Gaspar de Portolà to found missions and presidios at San Diego and Monterey (see Timeline of the Portolà expedition), thereby securing Spain's claim to the Pacific Coast harbors recommended by Cabrillo and Vizcaino. Two groups traveled from Lower California on foot, while a pair of packet ships (bearing supplies) traveled up the coast from the Baja California Peninsula.
Personal Experience: This is a beautiful mission which you can explore for free. It's a great spot for photoshoots and weddings and there's even a museum which covers the history of this mission and the surrounding area.