8. Colosseum, Rome
Once seating between 50,000 and 80,000 spectators who came through 80 entrances, the Colosseum was the world’s largest amphitheatre when it was built between AD70 and AD80 for sporting events and gladiatorial combat. Around two-thirds of the structure has been destroyed in the 2,000 years since but the remaining ruins are one of Italy’s most popular attractions. Take a walk inside, around the various levels, or fly overhead in these 360-degree images.