Old Town San Diego is considered the "birthplace" of California. San Diego is the site of the first permanent Spanish settlement in California. In 1769, Father Serra established the first mission. The mission and Presidio were built on a hillside. At the base of the hillside in the 1820's , a small Mexican community of adobe buildings was formed and by 1835 had attained the status of El Pueblo de San Diego.
In 1968, the State of California Department of Parks and Recreation established Old Town State Historic Park to preserve the rich heritage that characterized San Diego during the period from 1821-1872.
The San Diego Presidio was the first European settlement on the West coast. It was a military outpost of Spanish California (Alta California) founded by Gaspar de Portola in 1769. The Presidio and Mission were originally built on a bluff known as Presidio Hill, which is adjacent to Old Town State Park. After 5 years the Mission moved to a different location. Presidio Hill remained the primary settlement for several decades, because it was defensible against attack by European enemies or hotile Indians. In the 1820's, the town of San Diego grew up at the base of the bluff, at the site that is currently Old Town. The Presidio was abandoned and fell into disrepair.
During the pueblo period, the Old Town area was the commercial and governmental hub of the region, even though its population was not very large. In 1834, the Mexican government granted San Diego the status of a pueblo or chartered town, but the pueblo status was revoked in 1838 due to its declining population. The town's growth was limited due to its location being far from navigable water.
When California was admitted to the United States in 1850, San Diego; which consisted of mainly Old Town was made the county seat of San Diego County.
Old Town remained the heart of San Diego until Alonzo Horton began to promote development in what is now Downtown San Diego. Residents and businesses abandoned Old Town for Horton's New Town because of its proximity to shipping. In 1871, government records were moved to a new county courthouse in New Town.
The pictures for this post, I took in Old Town San Diego and the information I took from Wikipedia and the web site for Old Town.