Fodor's Expert Review Santo Stefano Rotondo
This 5th-century church is thought to have been inspired by the design of the Church of the Holy Sepulchre in Jerusalem. Its unusual round plan and timbered ceiling set it apart from most other Roman churches. So do the frescoes, which lovingly depict 34 of the goriest martyrdoms in Catholicism—a catalog, above the names of different emperors, of every type of violent death conceivable. (You've been warned: these are not for the fainthearted.)