A new visitor centre showcasing the archaeological remains of an ancient and mysterious temple to the Latin god Mithras has opened under Bloomberg’s new European headquarters in the heart of the City of London next to the Bank of England.

The London Mithraeum became an instant public sensation when it was first discovered by chance in 1954 on a World War II bomb site.

Up to 30,000 people per day queued to see the temple to Mithras before it was dismantled and reassembled 100 metres (330 ft) away from its original location so it could remain open to the public once post-war rebuilding on the site was complete.

Now, under the guidance of Foster and Partners, Bloomberg’s project has seen the ruins returned to their original site and restored, deep beneath the financial software, data, and media company’s vast new base.

Today visitors to the temple can descend through steep, black stone-lined stairs to seven metres below the City’s streets where nearly 2,000 years ago, when Londinium was founded by the Romans and the then smelly, but now long lost, river Walbrook once flowed marking the limits of the empire’s first settlement in Britain.

The temple to Mithras, the virile young god from the east, was built next to the Walbrook nearly 200 years after the first Romans came to England and a century after the mysterious cult of Mithras first appeared in Rome in the 1st century AD.

It had spread across the empire over the next 300 years, predominantly attracting merchants, imperial administrators and soldiers who worshipped him by the light of flaring torches in underground temples, where the blood of sacrificial animals soaked into the mud floor.

Meetings were held in the private, dark and windowless temples which were often constructed below ground.

The mythological scene of Mithras killing a bull within a cave, the ‘tauroctony’ was at the heart of the cult, and its full meaning is still subject of much speculation.

The reconstruction of his rites below Bloomberg’s building includes the soundtrack of shuffling sandaled feet, and voices chanting in Latin the names of the levels of initiates taken from graffiti on a temple in Rome.

The sounds accompany visitors as they descend deep below the modern financial giant’s sprawling new structure where they are confronted with more atmospheric audio, lights and misty haze to bring the ruin back to life.

Michael R. Bloomberg, Founder, Bloomberg LP said: “London has a long history as a crossroads for culture and business, and we are building on that tradition. As stewards of this ancient site and its artefacts, we have a responsibility to preserve and share its history. And as a company that is centred on communication – of data and information, news and analysis – we are thrilled to be part of a project that has provided so much new information about Roman London. We hope London Mithraeum Bloomberg SPACE will be enjoyed by generations to come.”

Bloomberg’s new site, which has taken seven years to build, occupies 3.2 acres and provides approximately 1.1 million square feet of sustainable office space, two new public spaces featuring specially commissioned works of art, a retail arcade that will reinstate an ancient Roman travel route, as well as the subterranean London Mithraeum Bloomberg SPACE itself.