VATICAN CITY (RNS) — In the 15^th century, the basilica that Emperor Constantine had built around the tomb of St. Peter was cracked and falling apart, having stood for 1,100 years. Through taxes, papal revenues and the controversial sale of indulgences, Pope Julius II launched its rebuilding in 1506, starting a project lasting 120 years and employing the most renowned artists of the time.

The basilica as we recognize it today was consecrated in November 1626, and for its 400th anniversary, the Vatican has partnered with the Italian energy giant Eni to create a digital twin of St. Peter’s to offer the famous structure a new form of enduring power.

“Pope Julius had to opt for the demolition and reconstruction of the church,” said Cardinal Mauro Gambetti, the archpriest of the basilica. “Today, Pope Leo can renew without demolishing, thinking serenely about this basilica, which pilgrims and visitors will be able to experience for the next four millennia.”

Gambetti made his remarks during a press conference showcasing the initiatives the basilica is launching to celebrate the fourth centennial, including its partnership with Eni in the project titled “Beyond the Visible.”

Eni employed 4,500 hours of work across 80,000 square meters, which include the previously unexplored foundations and subsoil of the basilica, to create a digital twin of St. Peter’s. The 3D model also allows experts to monitor the basilica’s structural stability by analyzing millimetric shifts on the order of a ten-thousandth of a degree. While Eni representatives refused to disclose the full cost of the project, Claudio Granata, the company’s director of relations and services, said it amounted to hundreds of thousands of euros.

“It’s money well spent,” he said, clarifying that the ownership of the basilica’s twin rests with the Fabbrica di San Pietro, the Vatican body overseeing the maintenance and restoration of the basilica.

The project also includes sensors designed to monitor visitor flows in real time, improve safety and manage interior spaces of the basilica, according to organizers. It will work in concert with a “smart pass,” which allows real-time booking to access St. Peter’s. Faithful pilgrims and tourists will be allowed to post images and content on an interactive hub.

The professionals hired by Eni had access to thousands of documents from the basilica’s archives, which shed light on the history and construction of St. Peter’s. The art historian Jacopo Veneziani, who stars in a documentary presenting the project, said he was surprised by the extraordinary role played by women in the construction and upkeep of the basilica.

“Women have been portrayed for centuries as muses and inspiration for male creators,” Veneziani said, but documents in St. Peter’s archives show they were architects, suppliers, restorers and artists. “We can describe many of them as entrepreneurs,” he said.

The documents also allowed them to digitalize the handwriting of Michelangelo Buonarroti — who designed the basilica’s dome and the Pietà statue housed inside — and it will be available for free as a font called “Michelangelus.”

The basilica joined forces with the Vatican department for communication to create an app containing liturgies, readings and hymns that can be translated into 60 languages in real time using tools powered by artificial intelligence. “This will allow people from all over the world to understand what is being celebrated,” Gambetti explained.

As part of the anniversary celebrations, the basilica will boast new artwork representing the Stations of the Cross created by the Swiss artist Manuel Dürr that will be inaugurated on Friday (Feb. 20). The event will be followed by meetings, prayers and songs by the basilica’s historic choir, the Cappella Giulia.

New areas of the basilica will be visible to tourists and pilgrims, including the Gregorian and Clementine cupolas and the octagonal rooms traditionally used for storage and closed to the public. Officials said the refreshments area and restrooms will be moved farther north to accommodate visitors.

Gambetti noted that over 20 million people pass though the basilica each year and there are plans to increase ecological sustainability, from the food served on site to the production of religious goods and souvenirs.

The numerous projects and activities will conclude in November when Pope Leo will hold a solemn celebration in the basilica.