The first inhabitants arrived at least 10,000 years ago. They lived off the land and fished off the coast. Explorer Juan Rodríguez Cabrillo encountered the bay and called it "closed and a very good port." Alonzo Horton likened the setting to a "Heaven on Earth" - "It seemed to me the best spot for building a city I ever saw" - and he proceeded to move the center from Old Town to today’s downtown in 1867.
"This mountainous region is full of charming valleys, and hidden among the hills are fruitful nooks capable of sustaining thriving communities," essayist Charles Dudley Warner wrote of San Diego in 1890.
Its 4,526 square miles encompass one of the richest habitats in the nation with multiple climate zones and an abundance of plants and animals, including about 200 endangered and threatened species, the most of any county in the nation.