Official description from Mission Dolores:
The Misión San Francisco de Asís was founded June 29, 1776. The settlement was named for St. Francis of Assisi, the founder of the Franciscan Order, but was also commonly known as "Mission Dolores" owing to the presence of a nearby creek named Arroyo de los Dolores, or "Creek of Sorrows."
Mission Dolores is the oldest intact building in the City of San Francisco and the only intact Mission Chapel in the chain of 21 established under the direction of Father Serra. The Mission has been a steadfast witness to the span of San Francisco's history including the California Gold Rush and the 1906 San Francisco Earthquake. The Mission Cemetery is the only cemetery that remains within the City limits. The Cemetery is the final resting place for numerous Ohlone, Miwok, and other First Californians as well as notable California pioneers.
Wikipedia excerpt:
Mission San Francisco de Asís, or Mission Dolores, is the oldest surviving structure in San Francisco and the sixth religious settlement established as part of the California chain of missions. The Mission was founded on June 29, 1776, by Lieutenant José Joaquin Moraga and Father Francisco Palóu (a companion of Father Junipero Serra), both members of the de Anza Expedition, which had been charged with bringing Spanish settlers to Alta (upper) California, and evangelizing the local Natives, the Ohlone. The settlement was named for St. Francis of Assisi, the founder of the Franciscan Order, but was also commonly known as "Mission Dolores" owing to the presence of a nearby creek named Arroyo de Nuestra Señora de los Dolores, meaning "Our Lady of Sorrows Creek." A member of the Anza Expedition, Friar Font, wrote about the spot chosen for the Mission: