ISABEL RUBIO ARROYO | Tungsteno

St. Peter's Basilica is not only the spiritual heart of Catholicism, but also a monument that encompasses centuries of art, architecture and mystery. From its origins in the time of Constantine to its underground nooks and passageways, this monumental temple continues to fascinate millions of faithful and visitors every year. Here are some of the most surprising and lesser-known facts about the world’s largest Christian church.

The history behind St. Peter's Basilica

The St. Peter's Basilica that we know today was not the first church to occupy this site. In the 4th century, Emperor Constantine commissioned a church to be built here, which stood for over a thousand years. However, it was not until 1506 that Pope Julius II decided to replace it with a new, monumental construction in tribute to the Apostle Peter, who is believed to have been buried on that very hill in the Vatican. Construction took almost 120 years and involved the participation of prominent Italian architects and artists such as Donato Bramante, Michelangelo and Raphael. While Bramante took inspiration from the Roman Pantheon for his initial design, Michelangelo was responsible for the iconic dome.

The imposing interior of St. Peter's Basilica. Credit: Fabbrica di San Pietro / St. Peter's Basilica

The largest Christian church in the world

This monumental work embodies the splendour of the Vatican. At 136.5 metres high, its dome is the tallest in the world. The interior covers more than 15,000 square metres and its total area extends to about 2.3 hectares. Recognised as a UNESCO World Heritage Site in 1984, it is considered the largest Christian church in the world.

View of the interior of the dome of St. Peter's Basilica. Credit: Fabbrica di San Pietro / St. Peter's Basilica

Saints welcome the faithful in the iconic St. Peter's Square

In front of the basilica, St. Peter's Square can host thousands of people. According to the Vatican's official website, Vatican News, more than 100,000 people attended Pope Leo XIV’s first greeting from the square. Designed by Gian Lorenzo Bernini, the square features an elliptical colonnade arranged in 284 columns in four rows, which symbolise the embrace of the Church. At its centre stands an Egyptian obelisk, flanked by two fountains. The square is adorned with statues of saints who welcome visitors and, according to the Vatican, represent the union between the heavenly and earthly churches.

St. Peter's Square and its iconic colonnade. Credit: Fabbrica di San Pietro / St. Peter's Basilica

The popes who rest beneath St. Peter's Basilica

Throughout history, St. Peter's Basilica has inspired numerous legends about hidden passageways and secret chambers beneath its structure. Beyond the myth, the truth is that there are several real underground spaces, such as the Vatican Grottoes and the Necropolis, which house ancient papal tombs. Although Pope Francis has chosen the Basilica of Saint Mary Major as his burial place, the remains of 91 popes lie beneath Saint Peter's. These papal tombs are located alongside those of members of royalty and nobility. Notable pontiffs buried here include emblematic figures such as Pius X and John Paul II. For archaeologists, this collection of tombs is a historical treasure of incalculable value.

The Vatican Necropolis. Credit: Fabbrica di San Pietro / St. Peter's Basilica

The Vatican's secret passageway

Very close to this monumental complex is the Corridor of Borgo, also known as the Passetto de Borgo, a fortified corridor connecting Vatican City with Castel Sant'Angelo. Although it doesn’t pass directly under the basilica, it forms part of the Vatican's defensive system and was constructed as an escape route for popes during times of crisis. The corridor’s most famous episode occurred during the Sack of Rome in 1527, when Pope Clement VII managed to escape through it and took refuge in the castle. According to Rome's Department of Major Events, Sports, Tourism and Fashion, “the Pope was saved by the skin of his teeth, running through the narrow corridor, while the courtiers and nobles who accompanied him protected him with a dark cloak to prevent his white robe from becoming an easy target.” Today, some sections of the Passetto can be visited on guided tours from Castel Sant'Angelo, revealing one of the most strategic and lesser-known corners of Vatican history.

View of the Passetto di Borgo from Castel Sant'Angelo in Rome. Credit: Rome's Department of Major Events, Sports, Tourism and Fashion

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ISABEL RUBIO ARROYO | Tungsteno

Almost 100 kilometres off the coast of Baku, in the middle of the Caspian Sea, rises Neft Daşlari, an industrial city built on platforms. Its name, meaning “Oil Rocks,” reflects its function: a vast network of extraction wells and processing plants linked together by kilometres of steel bridges. Accessible only by a lengthy boat ride from the mainland, this enigmatic city floats in the middle of the world's largest enclosed body of water.

A motorway in the middle of the sea

Founded in 1949, Neft Daşlari began with platforms built atop deliberately sunken ships. Over time, it evolved into a vast industrial city, linked by more than 200 kilometres of trestle bridges and supported by nearly 100 kilometres of pipelines transporting oil and gas. At its peak, the city boasted nearly 2,000 oil wells and some 320 production plants.

But Neft Daşlari is about more than industry—it has homes, shops, a theatre, a heliport and even a soccer field. Trees were even planted atop steel structures, and at its height, the city housed over 5,000 inhabitants. In recent decades, however, the population has dwindled and much of the infrastructure has fallen into disrepair, with some parts claimed by the sea.

Oil Rocks has served as the dramatic setting for numerous documentaries and films, including scenes from the 1999 James Bond film The World Is Not Enough. It has also inspired renowned Azerbaijani artists, such as composer Gara Garayev and artist Tahir Salahov. Filmmaker Marc Wolfensberger, who shot the movie Oil Rocks: City Above the Sea, described the site as “beyond anything I had seen before.” As he told CNN, it was like “a motorway in the middle of the sea” that stretched out “like an octopus.”

Trailer for the documentary Oil Rocks: City Above the Sea. Credit: Marc Wolfensberger

"The Island of Seven Ships," a symbol in Azerbaijan

To shield the structure from the wind and waves of the Caspian Sea, seven decommissioned ships were deliberately sunk, their hulls forming an artificial bay around the original island. “Some of those ships are visible on the surface of the water where they were buried,” Mirvari Gahramanli, head of the Oil-Workers Rights Protection Organisation, told CNN. In Azerbaijan some refer to Neft Daşlari as “the island of seven ships” and even “the eighth wonder of the world,” she added.

Today, the oil field remains operational. Over the decades, 1,983 wells have been drilled, with 432 still active. According to SOCAR, Azerbaijan’s state-run oil company and the operator of Neft Daşlari, the field produced an average of 2,865 tons of oil per day as of 1 January 2024. Since production began, the site has yielded a total of 179.8 million tonnes of crude oil and 14.092 billion cubic metres of natural gas. Peak output was reached in 1967, when it produced 7.6 million tonnes of oil—about 4.5% of the total cumulative volume.

The industrial city is still operational with more than 400 active wells. Credit: SOCAR

The uncertain future of the “floating” city

Neft Daşlari’s importance has declined in recent decades, overshadowed by the development of larger fields and fluctuating oil prices. “The production at Neft Daşlari supplies only a minor part of Azerbaijan's oil production,” explains Brenda Shaffer, an energy expert at the U.S. Naval Postgraduate School, who has advised oil and gas companies in the Caspian region. As output has declined, so too has the population, now estimated at around 2,000. Moreover, the floating city has not been without controversy: beyond the danger faced by those living or working there due to extreme weather conditions, Gahramanli has raised concerns about the discharge of raw sewage and reports of oil spills.

The floating city’s production now accounts for only a small share of Azerbaijan’s oil output. Credit: SOCAR

With its reserves gradually running dry, the future of this sprawling offshore settlement remains uncertain. Shaffer suggests it could one day become a tourist attraction. Filmmaker Marc Wolfensberger envisions a different future: “It’s really the cradle of offshore oil exploration,” he said, imagining it repurposed as a museum. As for the risk of it sinking—either due to structural fatigue or the effect of climate change—Mirvari Gahramanli was firm when asked by the BBC: “The island is not about to sink and, at the moment, no such risk is foreseen.”

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