A rotunda is a round building or room, especially one with a round bowl-shaped roof. a round building or hall, especially one with a dome (rotonda, from rotundus; ROUND). In Classical and Neoclassical architecture, a building or room that is circular in plan and covered with a dome. The Pantheon is a Classical Roman rotunda. The Villa Rotonda at Vicenza, designed by Andrea Palladio, is an Italian Renaissance example. The central hall of the U.S. Capitol is an example of the rotunda in its familiar role as part of a monumental public building