Eastern Orthodox church architecture constitutes a distinct, recognizable family of styles among church architectures. These styles share a cluster of fundamental similarities, having been influenced by the common legacy of Byzantine architecture from the Eastern Roman Empire. Some of the styles have become associated with the particular traditions of one specific autocephalous Eastern Orthodox patriarchate, whereas others are more widely used within the Eastern Orthodox Church. These architectural styles have held substantial influence over cultures outside Eastern Orthodoxy; particularly in the architecture of Islamic mosques, but also to some degree in Western churches. History While sharing many traditions, Eastern Christianity and Western Christianity began to diverge from each other from an early date. Whereas the basilica, a long aisled hall with an apse at one end, was the most common form in the West, a more compact centralised style became predominant in the East. These churches were in origin "martyria" focused on the tombs of the saints—specifically, the martyrs who had died during the persecutions of Christians, which only fully ended with the conversion of the Emperor Constantine (AD 337). They copied pagan tombs and were roofed over by a dome which symbolised heaven. The central dome was then often surrounded by structures at the four points of the compass producing a cruciform shape—these were themselves often topped by towers or domes. The centralised and basilica structures were sometimes combined as in the church of Hagia Sophia in Constantinople (construction began in AD 360). The basilican east end then allowed for the erection of an iconostasis, a screen on which icons are hung and which conceals the altar from the worshippers except at those points in the liturgy when its doors are opened. A variant form of the centralised church was developed in Russia and came to prominence in the 16th century. Here the dome was replaced by a much thinner and taller hipped or conical roof which, it is said, originated from the need to prevent snow from remaining on roofs. One of the finest examples of these tented churches is St. Basil's in Red Square in Moscow. For a long time, the art of architecture was primarily concerned with the design of churches and aristocratic palaces, therefore the evolution of Orthodox churches represents a major part of the history of Byzantine architecture and Russian architecture. More detailed information is presented in those articles. Unlike Western Christian architecture with