A dome is a common structural element of architecture that resembles the hollow upper half of a sphere. Domes do not have to be perfectly spherical in cross-section, however; it is sufficient that they simply be curved surfaces. A saucer dome is a dome section of large radius that caps a space with a low dome. A variant is the Onion dome that resembles more than half of a sphere, exemplified by Saint Basil's Cathedral in Moscow.

The concave triangular sections of vaulting that provides the transition between a dome and the square base on which it is set and transfer the weight of the dome are called pendentives. A less sophisticated version of a pendentive is a squinch..

A dome can be considered as an arch which has been rotated around its vertical axis. As such, domes have a great deal of structural strength. They can be constructed of ordinary masonry, held together by friction and compressive forces.

A half-dome forms the head of an exedra or its smaller version, a niche. In Late Antiquity, the exedra developed into the apse, with separate developments in Romanesque and Byzantine practice.

Famous domes

See also

• Geodesic dome
• Cupola
• Concrete dome
• Doming technique