Old Towne, Orange Historic District, a one square-mile around the original plaza of Orange, California, contains many of the original structures built in the period after the City's incorporation. It is a vibrant commercial district, containing Orange County's oldest operating bank and the oldest operating soda fountain. The Historic District was listed on the National Register of Historic Places in 1997 (#NPS-#97000617), and is the largest National Register District in California. The Old Towne Preservation Association is a non-profit organization dedicated to maintaining the district.
According to State Historic Resource Surveys, Orange is unique among the region and the state in that it has the second largest concentration of historic buildings. A list of all of the buildings and sites in Orange that appear in the National Register of Historic Places can be found at , , and .