Overview
An earthquake in 1117 brought down all but four arches of the outer ring, and what you see from the piazza is mostly the second wall; the interior tiers are largely intact, which is why it still works. The acoustics are unamplified, so a voice from the stage carries to the top step of the stone seating. In the intervals the audience lights candles on the terraces, a custom old enough that it now reads as part of the performance.
Highlights
Take the cheap stone steps rather than the padded stalls: it is the acoustically better half of the house and the tradition belongs there. Cushions are rented at the gate and are not optional on unshaded stone. Out of season the empty Arena is open by day on a ticket that also covers Castelvecchio and the Roman theatre.