Only 4km from Golden Sands is one of Bulgaria's most interesting landmarks. The Aladzha Rock Monastery is extremely unique but little is known about the true heritage of the site. Some historians believe that the bizarre rock formation may have been first inhabited in the 5th century BC. It may also have been used by monks until the 18th century, but it was not discovered again until 1928. Walk among the extraordinary medieval ruins to see the astounding construction with catacombs, walkways and stairs carved into the cliff-side 40m above ground level. Over time erosion has caused damage to the monastery's murals, but it's still a remarkable sight to see.