One of the most popular of Villa Gregoriana’s natural treasures is the Valle dell’ Infierno, or Valley of Hell. This valley lies a short hike from the entrance and is known mostly for the waterfall at the end of the hike. You descend into the infamous valley from the lovely Gregorian bridge that connects Tivoli's historic center to the park.

Pope Gregory XVI had the river redirected through the Mount Catillo tunnel during the construction of Villa Gregoriana. This huge tunnel will now be the first stop on your Villa Gregoriana tour. This tunnel is a great spot for taking photographs, however, it is often crowded because of its proximity to the entrance.

You will pass interesting locations on your way to Villa Gregoriana, like the ruins of Manlio Volpiscus' first-century Roman villa, which Roman authors Horace and Statius praised in ecstatic terms. Even though the villa is not in a state that could dictate its former beauty, its scale is still a hauntingly beautiful sight.

The Tiburtine Acropolis is situated on a rocky spur and has two temples: the Sybil, which has a rectangular layout, and Vesta, which has a round plan. The Temple of Vesta has evolved over time to become the symbol of Tivoli. It was rediscovered in the Renaissance era of the 19th century and was a favorite subject of Romantic landscape painters.

Neptune’s Grotta is one of only two cave systems found near the Villa Gregoriana. It sparks great tourist interest because of its historical significance. The Aniene river flowed through Neptune’s Grotta before it was diverted and assumed its current appearance. The unique hydraulic construction is worth your time.

The Siren’s Grotta is the second cave system in the Villa Gregoriana complex. The narrow walkway and small yard leading to the caves are truly a place of serene elegance. The Siren’s Grotta is also known as the Mermaid’s Cave because of the well-carved stones and the sensory beauty of the area.

The Great Waterfall is not only called so because of its history and antiquity. The waterfall has a drop of over 130 meters, making it a grand view for tourists. There is a viewing platform at the base of the waterfall that provides a great view of this majestic waterfall.

The Nymphaeum is a Roman-era artificial cave built on a cliff where there was likely a different waterfall. The Aniene River was channeled even in Roman times to prevent flooding and to supply a network of mills, remnants of which have been discovered.

You will thoroughly enjoy the walk through the eerie Percorso Moillis, which was carved out of the mountain in 1809 to make it simpler for painters and other visitors to reach the abyss. Back in the day, artists and visitors had to be lowered down into the chasm using ropes.