The Arènes de Lutèce are the only surviving ruins of the Roman conquest of Paris (formerly known as Lutetia), along with the remains of the public baths at Cluny... This amphitheatre once seated over 15,000 people. Probably built in the first century AD, it fell into ruin in the third century AD and was rebuilt in the 6th century. The remains were discovered during various excavations in the area in the late 18th and early 19th centuries. Now classed as a historical monument, the site is open daily and can be visited free of charge.