St. Peter’s Basilica gets a digital makeover with AI

As soft instrumental ambient music plays, AI-enhanced images, video projections, and bright text roll across an exhibit space above the western wing of St. Peter’s Basilica, recounting the story of the construction of the biggest Catholic church in the world and of the life of the first bishop of Rome. Viewers seem to float across the Basilica’s large atrium, as images zoom in on details of the baldachin, the Chair of St. Peter, and more. 

The Pétros ení (meaning “Peter is here”) exhibition is one of several initiatives launched by St. Peter’s Basilica in partnership with Microsoft, which together created a digital twin of the Church using 400,000 drone photos and artificial intelligence. The historic Basilica enters a new digital era with innovative interactive and immersive experiences accessible to all, just in time for the 2025 Jubilee, which is expected to gather around 30 million pilgrims. 

“This house of prayer for all peoples (cf. Is 56:7; Mt 21:13) was entrusted to us by those who have preceded us in faith and in the apostolic ministry,” Pope Francis told the representatives of this massive project in a meeting on November 11 at the Vatican. “Therefore, it is a gift and a task to take care of it, both in a spiritual and material sense, also through the most recent technologies."

“St. Peter's Basilica is like the starry sky on a summer night: You remain enchanted by its splendor, its munificence,” said Cardinal Mauro Gambetti, Archpriest of St. Peter’s Basilica, during a press conference at the Vatican on November 11. However “it takes an astrolabe, a monocular and a telescope to learn about the stars; and it takes a spacecraft to penetrate the starry sky.” 

With this analogy in mind, Cardinal Gambetti explained that the Vatican partnered with Microsoft in 2022 to try and create adequate technological tools that would make accessible and comprehensible the history and spiritual significance of St. Peter’s Basilica to the over 40,000 people that visit it daily. Microsoft’s AI for Good Lab and the French company Iconem, specialized in digital preservation of cultural sites, used drones, cameras, and lasers and photogrammetry technology to produce over 400,000 high-resolution images of every angle and detail of the Basilica.

Flown over the course of four weeks, when there were no visitors, the drones collected enough data to fill up 5 million DVDs. Microsoft then used these photos and artificial intelligence to generate a virtual reconstruction of St. Peter’s Basilica, a digital twin, that served to build the new interactive experiences and also helped identify critical points in the structure that needed to be restored, such as cracks. 

“It is literally one of the most technologically advanced and sophisticated projects of its kind that has ever been pursued,” said Brad Smith, Vice Chair and President of Microsoft, at the press conference. “When you think about this partnership I think it is as extraordinary as the project itself because it brings together one of the oldest and most important institutions in the world with the newest technology humanity has created.” 

The Pétros ení exhibit will allow visitors to enter into the Basilica’s history and discover the life of St. Peter in a new way, through the AI-enhanced images that take the viewer across space and time. It is divided into two spaces both located on the terrace above the west wing of the Basilica. Additionally a new website (virtual.basilicasanpietro.va) for St. Peter’s will also feature a virtual tour, made with the digital twin of the Basilica, which will allow people all over the world to visit the Church from the comfort of their own devices.

Although Smith highlighted that virtually visiting a place will never replace the physical experience of going to a new location, he underlined how the tour allows people who may not have the opportunity to visit Rome to discover the Basilica. While it is unclear when the physical exhibition will open to the public and its cost, the new website should be available in early December. 

These projects allow people to see “the basilica like no generation has ever seen it before, to go from the tombs underneath the floor, all the way to the top of the dome, [...], to understand what an extraordinary place it is,” Smith said.

“If people entering the Basilica in any way will have sensed the Mystery that inspired and radiates it, our mission will have been fulfilled,” Cardinal Gambetti said. 

The new website will also try to make the visitor experience more seamless by allowing people to book their tours beforehand, by showing in real time the number of visitors present in the Basilica, and featuring Mass times and other important information. It will also feature audio and text description that can help visitors learn more about the Church as they are visiting it, similar to the concept of audioguides. 

Additionally the Basilica and Microsoft will launch a partnership in January 2025 with Minecraft for education, which uses the videogame Minecraft, centered on building, for educational purposes for students. It will feature another virtual version of the Basilica that the game users will be able to access. 

Other than allowing visitors and pilgrims to discover the history of the Basilica in a new way, the digital twin will also help the Fabric of St. Peter, the institution that helps maintain and preserve the Basilica, in its mission. Using algorithms and the AI images of the digital twin, the project was able to highlight missing mosaic tiles or structural vulnerabilities such as cracks in the Basilica’s sprawling structures.

“We saw in the images of the dome [of St. Peter’s Basilica], where the mosaic of the Eternal Father is, that there are little spider nests, which now we will have to try to remove so it will shine even more,” Cardinal Gambetti explained. 

“We now have a model that literally will live forever in the perfect digital form of what this building looks like in 2024,” Smith said. “So just like we are the beneficiaries of the heritage of what [Michelangelo or Bernini] created, I hope that future generations will find some use of this new heritage that we literally are creating for them.”