Hidden inside the Palazzo della Pilotta is the Teatro Farnese, the most extraordinary surviving Baroque theatre in Europe — a vast U-shaped auditorium built entirely in wood and painted to look like marble. Completed in 1618 by Aleotti as an opera house for the Farnese court, it could seat 3,000 spectators and was the first theatre with a proscenium arch designed for fully movable scenery.
The original was almost entirely destroyed in the 1944 bombing; what you see now is a faithful postwar reconstruction in wood. The space is open as part of the Galleria Nazionale visit; standing on the stage and looking out at the empty tiers is a rare and slightly eerie experience.