Although I believe both monuments are must-sees for first-time visitors, the Italian city is home to many other sites that are just as historic and awe-inspiring. Plus, with Italy's tourism numbers already hitting record levels last year, avoiding crowds will likely be as important as ever this summer.

On your next trip to Rome, forgo the Colosseum and the Vatican Museums and check out these underrated, less crowded monuments instead. Located steps away from the iconic Piazza Navona square is Palazzo Altemps, a 15th-century aristocratic villa that was inhabited by the Altemps family for centuries.