The Temple of Orithena was founded in −2850 by Adrakhones, the father of geometry on Arbre. As an institution of learning, it is analogous to a Pythagorean school. Destroyed by volcanic erupation in −2621, its destruction lead to the beginning of the Peregrin period. Many of the survivors gravitate toward the city-state of Ethras. Prominent features of the temple include an Analemma on the temple floor, which is open to the sky, as well as a regular decagon on which the problem of the Teglon can be explored with tiles made from the original molds.