Built of travertine limestone, tuff (volcanic rock), and brick-faced concrete, it is estimated that 65,000 spectators witnessed gladiatorial contests and public spectacles including animal hunts, executions, re-enactments of famous battles, dramas based on Roman mythology, and briefly, mock sea battles in the Colosseum. The Colosseum is an elliptical amphitheatre located in the centre of the city of Rome and stands as the largest ancient amphitheatre ever built. Despite its age (almost 2000 years old), it is still the largest standing amphitheatre in the world. Today, the Colosseum is listed as one of the new 7 Wonders of the World.