The home was built atop ancient ruins. Conforti told Vatican News that the basement houses “an artificial canal that served the thermal baths of Agrippa” as well as the tomb of Aulus Irtius, “one of the commanders of the Roman army in Gaul of Julius Caesar.”

Engineer Mauro Tomassini, meanwhile, said the structure “is still being studied today” because it “is not fully known.”

Describing the building as “an apparent fortress, with four corner towers,” Tomassini said that it “has so many things to offer to those who visit it,” though he claimed that “unfortunately probably the Romans themselves do not attend it and do not know it as they should.”

At the opening, Galantino indicated the special presentation was motivated by Pope Francis’ repeated calls for a more transparent Church.

“But transparency does not consist only in the publication of the budget,” Galantino said. “It does not stop at the ‘quantity’ but also shows the quality of what is kept. This is a step forward.”

The Vatican lists the building as housing the Supreme Tribunal of the Apostolic Signatura, which the Holy See says “ensures that justice in the Church is correctly administered.”