Rome is the city with the highest concentration of historical and architectural monuments in the world; its historic center bounded by the perimeter of the Aurelian walls, overlapping testimonies of almost three millennia, is an expression of the historical, artistic and cultural world of Western Europe and, in 1980, along with the extraterritorial properties of the Holy See in the city and the Basilica St. Paul Outside the Walls, was listed as a UNESCO World Heritage Site.

Rome, the heart of Catholic Christianity, is the only city in the world to accommodate internally a foreign state, the enclave of Vatican City: for this reason it is often called the capital of two states. Over 16% of the world's cultural heritage is located in Rome (70% in Italy).