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.

The architecture of Russia refers to the architecture of modern Russia as well as the architecture of both the original Kievan Rus', the Russian principalities, and Imperial Russia. Due to the geographical size of modern and Imperial Russia, it typically refers to architecture built in European Russia, as well as European influenced architecture in the conquered territories of the Empire.