templon (from Greek τέμπλον meaning "temple", plural templa) is a feature of Byzantine architecture that first appeared in Christian churches around the fifth century AD and is still found in some Eastern Christian churches. Initially it was a low barrier probably not much different from the altar rails of many Western churches. It eventually evolved into the modern iconostasis, still found in Orthodox churches today. It separates the laity in the nave from the priests preparing the sacraments at the altar. It is usually composed of carved wood or marble colonnettes supporting an architrave (a beam resting on top of columns). Three doors, a large central one and two smaller flanking ones, lead into the sanctuary. The templon did not originally obscure the view of the altar, but as time passed, icons were hung from the beams, curtains were placed in between the colonnettes, and the templon became more and more opaque. Sometime between the 11th and 14th centuries, icons and proskynetaria began to be placed in the intercolumnar openings on the templon. After the reconquest in 1261, carving on the medieval templon approached sculpture in the round. The first ceiling-high, five-leveled Russian iconostasis was designed for the Cathedral of the Annunciation in Moscow Kremlin by Theophanes the Greek in 1405, and soon copied by his assistant Andrey Rublyov in the Cathedral of the Dormition in Vladimir in 1408.