The San Buenaventura Conservancy is an historic preservation organization in Ventura, California also known by its early name of San Buenaventura. It works to recognize and revitalize historic, archeological and cultural resources in the region. The Conservancy is a membership based historic preservation non-profit 501c3 organization. The group was formed in 2004 after the demolition of the Mayfair Theater, an S. Charles Lee, Streamline Moderne, movie theater in downtown Ventura, California that was razed and replaced with a condo project.