From Italian for "round", it's a large & high circular hall in a building, usually surmounted by a dome
List of Famous Italian Renaissance Buildings 
... Florence was the imposing Palazzo Vecchio (town hall), looking out onto the 
Piazza ... As early as 1367, its architects had envisioned a very tall dome to span 
the .... On one side the ground floor originally opened through large, round 
arches... [DOC] [TLE] Glossary - Web Gallery of Art [PAR] Its large, jagged leaves, curving in slightly at the tips, have been a favorite 
ornamental .... A semicircular projection, roofed with a half-dome, at the east end 
of a ... of Gothic architecture (distinct from the round arch of the Romanesque 
period).