Rotunda (architecture)
A rotunda (from Latin rotundus) is any building with a circular ground plan, sometimes covered by a dome. It can also refer to a round room within a building (a famous example being within the United States Capitol in Washington, D.C.). The Pantheon in Rome is a famous rotunda. A Band Rotunda is a circular bandstand, usually with a dome.
Read more about Rotunda (architecture): Rotunda in Central Europe