Old Town San Diego State Historic Park, located in the Old Town neighborhood of San Diego, California, is a state protected historical park in San Diego. It commemorates the early days of the City of San Diego and includes many historic buildings from the period 1820 to 1870. The park was established in 1968. In 2005 and 2006, California State Parks listed Old Town San Diego as the most visited state park in California.

Old Town is a neighborhood of San Diego, California. It contains 230 acres (93 ha) and is bounded by Interstate 8 on the north, Interstate 5 on the west, Mission Hills on the east and south. It is the oldest settled area in San Diego and is the site of the first European settlement in present-day California. It contains Old Town San Diego State Historic Park and Presidio Park, both of which are listed on the National Register of Historic Places.