Pompeians had a lively appreciation for the arts and had two semi-circular theaters for enjoying less violent spectacles than were held at the amphitheater. The larger, open-air version held 5000, had a canopy system similar to the arena's, and was used primarily for plays. With a curtain that could be raised and lowered between acts, it functioned identically to theaters today. The smaller was for music or other performances requiring a quieter environment. It once had a roof (long gone) and held about 1500.
An adjoining arcade and courtyard was for socializing before the shows and stretching during intermission. Nasty Emperor Nero later had this area converted into housing and practice space for the amphitheater's gladiators. You can easily make out the remains of the cells they occupied.
Il Piccolo and Grande Teatros are very greatly preserved. They are not far from the Forum next to one another in the lower part of Pompeii. It's a great place to sit down, although you can't sit in the theatre seats because they are blocked off but you can sit on the theatre steps, and enjoy an orange and truly understand where it is you have come to.
This large space was once used by the spectators of the two nearby theatres to stroll during intermissions between shows, or take shelter in case of rain. The gladiator weapons found here have suggested the hypothesis that, during the final years of the city, the building was used as barracks for the gladiators.