The Diego Sepúlveda Adobe is an adobe structure in Costa Mesa, Orange County, California. The adobe was built between 1817 and 1823 to house the mayordomo and herdsmen who tended the cattle and horses from Mission San Juan Capistrano to the south, in Alta California. The way-station was strategically situated on the banks of the Santa Ana River, some six leguas north of the parent mission, and also served as a lookout post when the French privateer Hippolyte de Bouchard attacked San Juan Capistrano on December 14, 1818. By 1820 the building and its surrounding lands became an official estancia, where padres from the mission would visit regularly to bring “spiritual food” to the faithful.