Teatro Scientifico del Bibiena is one of Mantua's loveliest interiors, a small 18th-century theatre where tiers of boxes wrap the room with theatrical precision. It was built for performance and learned display, and it still feels like a place where architecture is part of the spectacle.
The famous detail is that the young Mozart performed here soon after it opened, but the room would be worth seeing without that anecdote. Step inside if it is open; the visit is short, beautiful, and easy to combine with the nearby historic centre.