Trastevere's Two Underground Churches, in a Group of Ten

Trastevere is walked over more than it is walked into. Two of its churches have older churches underneath them, and this walk goes down into both. The group is capped at ten people and runs in one language only. Underground rooms are small and the stairs are narrow, so the number matters more here than it would above ground. One detail to read before booking, because it decides what you actually see. The underground level of the Basilica di San Crisogono opens Monday to Friday from 4:00 PM to 7:00 PM, and all day on Saturday and Sunday. A weekday morning departure cannot go down there. The guide replaces it with other monuments and the walk runs its full length either way. The Cavallini room at Santa Cecilia works the other way round: it is part of the morning option only. Between the two, no single departure sees everything, which is worth knowing when you choose a time slot. What is constant is the descent under Santa Cecilia, where the mosaic floor of a 3rd-century Roman house is still in place and the earlier basilica has kept its shape. Above ground the route runs through the cobbled back streets, past the door of San Crisogono that gives no hint of the Bernini apse behind it, and ends at Santa Maria in Trastevere with its gold mosaics catching whatever light is in the square.