Vatican Grottoes

The Vatican Grottoes are a series of underground chambers and chapels located under part of the nave of St. Peter's Basilica in the Vatican. They are situated three meters below the current floor, and extend from the high altar (the papal altar) to about halfway down the aisle, forming a true underground church that occupies the space between the current floor of the Basilica and that of the old Constantinian basilica of the 4th century.

The Vatican Grottoes are not to be confused with the Vatican Necropolis, which is an ancient burial ground that dates back to the Roman times and lies at a lower level beneath the Grottoes and the Basilica.

History and development

Origins

The origins of the Vatican Grottoes date back to the 16th century, specifically around 1590–1591, when they were constructed to support the floor of the Renaissance-era St. Peter's Basilica. The initial concept was proposed by architect Antonio da Sangallo the Younger to Pope Leo X following Raphael's death in 1520.¹

Pope Clement VIII, in 1592, undertook significant renovations of the medieval crypt, naming it the "Clementine" and installing a seventeenth-century altar near the tomb of Saint Peter. Between 1616 and 1617, Pope Paul V added straight corridors leading to the Confessio of Saint Peter,² along with several chapels such as the Chapel of the Salvatorello and the Chapel of the Madonna of Bocciata,³ adorned with hagiographic paintings by Giovanni Battista Ricci.

In the 17th century, under Pope Urban VIII, four small oratories were created at the base of the pillars supporting the dome, designed by and decorated by artists like and .