Russian architecture has been predominantly religious. Churches were for centuries the only buildings to be constructed of stone, and today they are almost the only buildings that remain from its ancient past. The basic elements of Russian church design emerged fairly early, around the eleventh century. The plan is generally that of a Greek cross (all four arms are equal), and the walls are high and relatively free of openings. Sharply-sloped roofs (tent roofs) and a multitude of domes cover the structure. The characteristic onion dome first appeared in Novgorod on the Cathedral of Sancta Sophia, in the eleventh century. On the interior, the primary feature is the iconostasis, an altar screen on which the church's icons are mounted in a hierarchical fashion.
The centers of medieval church architecture followed the shifting dominance of old Russia's cities--from Kiev to Novgorod and Pskov, and, from the end of the 15th century, Moscow.