Onion dome

An onion dome is a dome whose shape resembles an onion. Such domes are often larger in diameter than the tholobate (drum) upon which they sit, and their height usually exceeds their width. They taper smoothly upwards to a point. It is a typical feature of churches belonging to the Russian Orthodox church. There are similar buildings in other Eastern European countries, and occasionally in Western Europe: Bavaria (Germany), Austria, and northeastern Italy. Buildings with onion domes are also found in the Oriental regions of Central and South Asia, and the Middle East. However, old buildings outside Russia usually lack the construction typical of the Russian onion design. The origin of the design is thought to be the native architectural style of early Rus' tribes. Other types of Eastern Orthodox cupolas include helmet domes (for example, those of the Dormition Cathedral in Vladimir), Ukrainian pear domes (St Sophia Cathedral in Kyiv), and Baroque bud domes (St Andrew's Church in Kyiv) or an onion-helmet mixture like the St Sophia Cathedral in Novgorod. According to Wolfgang Born, the onion dome has its origin in Syria, where some Umayyad Caliphate-era mosaics show buildings with bulbous domes. An early prototype of onion dome also appeared in Chehel Dokhter, a mid-11th century Seljuk architecture in Damghan region of Iran. It is not completely clear when and why onion domes became a typical feature of Russian architecture. The curved onion style appeared outside of Russia, both in the Western world and in the Orient at a later time. But still several theories exist that the Russian onion shape was influenced by countries from the Orient, like India and Persia, with whom Russia has had lengthy cultural exchange. Byzantine churches and architecture of Kievan Rus were characterized by broader, flatter domes without a special framework erected above the drum. In contrast to this ancient form, each drum of a Russian church is surmounted by a special structure of metal or timber, which is lined with sheet iron or tiles, while the onion architecture is mostly very curved.