6. Colosseum
Another world famous building is the Colosseum in Rome. Considered as the most permanent work that gives clues about the life style of ancient Rome, it has the feature of being the most tourist attraction of Rome. This structure, in which the ancient Roman kings organized competitions for their personal tastes, was used for human and wild animal fights. In this sense, the building, which is considered as the bloodiest arena in the world, has witnessed the death of thousands of gladiators and tens of thousands of wild animals.