Notice of the ceremonies of reading of the Bull of indiction of the Jubilee of 1825 (Leo XII, Quod hoc ineunte saeculo, 24 May 1824), in the four patriarchal basilicas among which the Basilica of Santa Maria in Trastevere, substituted for St. Paul's
Even before this turns of events, the Basilica in Trastevere had served as a back-up to St Paul’s which, more distant from Rome’s built-up area given its location outside the walls and right by the Tiber, had been taken off the roster of compulsory pilgrim visits during the Jubilee of 1625 owing to an outbreak of plague in southern Italy; the Basilica in Trastevere also filled this function for eight days in 1700 after the Tiber burst its banks.
Diario di Roma, n. 102, 22 December 1824