An archaeological survey in Rancho Bernardo, a suburb of San Diego, revealed the presence of a circular rock structure on a Late Prehistoric site associated with a village complex in the Westwood Valley. Investigation of the feature reveals that it is an horno, or oven, similar to those introduced through Spanish settlement in the late 1700s. Several historic artifacts, associated with subsurface charcoal, ash and remains of prehistoric occupation, prompted a study of early land use in the area, that indicates potential construction and use by either indigenous or intrusive cultures.