Rotunda

A rotunda is any roofed building with a circular ground plan, sometimes covered by a dome, and the word can also describe a round room inside a larger building; it comes from the Latin rotundus, meaning round. The type includes the tholos, a rotunda enclosed by a wall, and the monopteros, a circular colonnade supporting a roof with no walls, while a band rotunda is a circular, usually domed bandstand. The Pantheon in Rome is the most famous and most influential rotunda, its design shaping later examples such as the rotunda beneath the dome of the United States Capitol in Washington, D.C.