In the second half of the 20th century, an Austrian archaeological mission cleaned up the ruins of St. John's Basilica and rebuilt the confession (the tomb of a saint, martyr or the vestibule leading to his tomb placed under the main altar, or the altar) of St. John.

Work recently carried out thanks to the support of a religious foundation from Lima (a city in the USA in Ohio) led to the reconstruction of some of the columns and walls of the basilica.