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. 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 Cavallini room at Santa Cecilia, with his Last Judgement, is part of the morning option only; the afternoon departure does not include it. And if a section of either basilica is shut on the day, the guide points out other monuments instead and the walk runs its full length either way. 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.