Kastalia of Delphi, the nymph of the prophetic springs of the Delphic Oracle. Theodorias (modern Qasr Libya) was a Byzantine city in the Cyrenaica, founded in 539 by the emperor Justinian and named in honor of his wife, the Empress Theodora. The history of Qasr Libya goes back to the Greek period (4th century BC), when it was called Olbia. The complex contained two churches: the eastern church, discovered in 1957, and the western church, discovered in 1964. The mosaics were excavated from the nearby eastern church after they were discovered by Libyan laborers. The collection contains 50 panels, mostly of animals, gods, goddesses, nymphs, and famous landmarks like the Pharos light house of Alexandria. These mosaic are among the greatest artistic treasures of Libya. Roman mosaics are constructed from geometrical blocks called tesserae, placed together to create the shapes of figures, motifs and patterns. Materials for tesserae were obtained from local sources of natural stone, with the additions of cut brick, tile and pottery creating colored shades of, predominantly, blue, black, red, white and yellow.