Right next to the theatre and entered on the same ticket, the amphitheatre is the larger and more ruinous of the pair, but no less atmospheric. Built for gladiatorial combat and wild beast hunts, its oval arena, two cavea tiers, and underground service tunnels are all clearly legible from the surviving walls. Local tradition holds that early Christian martyrs, including Saint Eulalia, were killed here.
You can walk down into the arena and stand where the gladiators stood; the acoustics of the stone bowl are still surprising. The site flows directly into the Roman Forum excavations to the north, and across a footbridge into the Museo Nacional de Arte Romano. Go to the amphitheatre first thing in the morning if you want it to yourself; tour groups arrive from Seville by mid-morning.