The ten colossal heads from San Lorenzo originally formed two roughly parallel lines running north @-@ south across the site . Although some were recovered from ravines , they were found close to their original placements and had been buried by local erosion . These heads , together with a number of monumental stone thrones , probably formed a processional route across the site , powerfully displaying its dynastic history . Two of the San Lorenzo heads had been re @-@ carved from older thrones .