Tomb of the Julii, Ancient tomb in Vatican City
The Tomb of the Julii is located beneath St. Peter's Basilica.
This early Christian burial site dates to the 3rd-4th century AD.
It features a mosaic with the Chi-Rho symbol, one of the earliest forms of Christogram.
Access to the tomb is controlled by the Vatican and subject to specific conditions.
The tomb is renowned for its richly decorated ceiling mosaic.
Source: Wikimedia