Private Underground Rome: Stadium, Bone Crypt, City of Water

Three sites below street level, visited privately, and each one underground for a different reason: one was buried by the city growing over it, one was dug deliberately, one is still full of water. Before booking, one thing needs saying. The archaeological area under Piazza Navona is currently closed to the public, with an official notice at the entrance and no announced reopening date. If the Stadium of Domitian is the reason you are booking, confirm with the operator that it is open on your date. The stadium was built by Domitian for the Capitoline Games, the first permanent masonry arena in Rome for athletic competition rather than for gladiators. Piazza Navona above it has the stadium's exact footprint, which is why the square is shaped like a running track. The Capuchin Crypt on Via Veneto is the opposite kind of place. The bones of roughly 3,700 friars were used as the decoration of five small chapels: each room is arranged around a different part of the skeleton, and the effect is more careful than macabre, since the point being made was about mortality and the friars made it on themselves. Vicus Caprarius, under the Trevi district, ends the walk with the Aqua Virgo still running through Roman masonry. Cancellation here is three full days, not twenty-four hours.