Uncovering the story of Roman London’s mysterious Mithraeum

In November 2017 one of London’s most famous Roman sites reopened to the public after spending several years hidden away in storage.  The Mithraeum, a subterranean temple dedicated to the god Mithras, has had an eventful afterlife since its celebrated rediscovery in 1954.  Moved from its original site to make way for a new office development, it was reconstructed at a new location nearby before the great wheel of redevelopment turned again and offered the chance for the Mithraeum to be reinstated at its original location on the banks of the now-underground river Walbrook.  The Mithraeum offers modern Londoners a glimpse into one of the Roman period’s more unusual elements: the secretive cult of Mithras, and the work to restore its ruins to the banks of the Walbrook also gave archaeologists an incredible opportunity to discover more about Roman-era Londinium.

Londinium was founded by the Romans in about 43AD, and at its height in the 2nd Century it covered an area roughly the same as that now occupied by the City of London.  It was an important military base, a busy port, and a site where many roads converged.  It was the Romans who first built London Bridge, close to where the modern London Bridge stands today.  Goods from all over the empire were traded in London, and the city was home to many merchants.  Archaeological investigations have uncovered evidence that Londinium’s population was a diverse and cosmopolitan one, with a number of Roman-era individuals found buried there having their origins in other parts of the Roman Empire, including a woman found buried in an ornate sarcophagus under modern-day Spitalfields Market who is thought to have been born in Rome.

Before the adoption of Christianity as the Roman Empire’s official religion by the Emperor Constantine in the early 4th Century, a wide variety of different deities were worshipped by those living in the Roman Empire.  Local gods were often co-opted into the Roman pantheon when new territories were conquered, with similarities between local and Roman gods being found and celebrated.  This fairly tolerant approach to local gods probably helped conquered peoples to assimilate into the Roman Empire.  Londinium would have been home to a number of temples, large and small, not to mention private shrines within people’s homes.  Evidence for the worship of many gods has been found in London: well-known Roman gods such as Jupiter and Minerva, as well as gods from further afield – evidence has been found for the worship of the Egyptian deities Anubis and Isis in London.  The site we are visiting today is associated with Mithras, a deity whose origins are thought to have originated in ancient Persia with Mithra, one of the Divinities associated with the Zoroastrian religion.

Roman veneration of Mithras seems to have centred on the story of him slaying a bull in a cave and later enjoying a feast with the sun god Sol, with much Mithraic imagery focusing on the sun, moon and stars. The Roman incarnation of the cult of Mithras appears to have diverged considerably from its Persian origins, although Roman depictions of Mithras commonly show him wearing a Phrygian cap, identifying him as coming from Persia.   Frustratingly for those researching Mithraism, no written sources of the story of Mithras have survived, so much of what is known about the cult has been derived from the artefacts and images uncovered in Mithraea.

There is a considerable amount of debate and uncertainty around both the veneration of Mithras, and what took place in the place where he was worshipped, the Mithraeum. Hundreds of Mithraea have been found at sites from all over the Roman Empire, including four in Britain – the London Mithraeum, plus two discovered at Hadrian’s Wall and another in Wales.  No documentary evidence has been found about the rituals that took place in Mithraea, and what we do know – or have guessed – has been gleaned from archaeological evidence found in the Mithraea themselves.  Each Mithraeum so far discovered has a similar layout, suggesting some uniformity in ritual between different locations.  These buildings are always subterranean – Mithras was said to have slain the bull in a cave – and are oblong in shape, with raised benches on either side of a central nave.  The focal point of the Mithraeum was the tauroctony – the scene of Mithras slaying the bull, which might have been a statue, a carving or a painting – with three altars dedicated to Mithras in front of the tauroctony.  Within the Mithraeum adherents of the cult went through their initiations (thought to have seven stages, or ‘ordeals’, in total), and also shared meals together.

It appears that only men took part in the worship of Mithras.  Around 1,000 named individuals who were said to worship Mithras have been discovered in the archaeological record, but all of these people are men.  It’s quite possible that the men who gathered at the Mithraeum were members of the army, prominent merchants and wealthy citizens.  The many Mithraea discovered around the Roman Empire are fairly small structures, suggesting that only a select number of people were chosen to join the cult.

The Mithraeum in Londinium has much in common with other Mithraea discovered elsewhere, in terms of its size, shape and layout. The tauroctony belonging to London’s Mithraeum, pictured below, was actually discovered in 1889, many years before the Mithraeum itself was identified.  This particular example shares many features common to other tauroctonies that have been discovered: it shows Mithras surrounded by the wheel of the zodiac, while the sun and moon gods look on.  The inscription on the right hand side has been translated as “Ulpius Silvanus, veteran of the 2nd Legion, initiated into a Mithraic grade at Orange, France, paid his vows to Mithras.”  Perhaps Ulpius Silvanus founded the Mithraeum in Londinium, or paid for the manufacture of the tauroctony.

London’s Mithraeum is thought to have been founded in about 240AD, and was in use for about 80 years.  After this time, the building was converted into a temple dedicated to another god, thought to be Bacchus.  By the 4th Century it appears that Mithraism had become less popular all across the Roman empire, which perhaps suggests why the building that housed the Mithraeum in Londinium was converted to another use. A number of statues from the Mithraeum were found carefully and respectfully buried on the site – the conversion of the Mithraeum to a different place of worship does not seem to have involved a violent iconoclasm.  In a society where many different deities were venerated, it is perhaps unsurprising that some gods enjoyed periods of vogue before becoming more obscure when other gods gained in popularity.

After the Roman army left Londinium, and the province of Britannia, in 410AD, the building that was once the Mithraeum fell into ruin.  Although it’s almost certain that people continued to live and work in the area, Londinium ceased to function as a city, and in later centuries the heart of Saxon London was further west, close to modern-day Aldwych.  The ruins of Roman buildings gradually disappeared under the soil and were forgotten. Eventually the City of London began to develop again in the 9th Century as its inhabitants sought protection from Viking raids behind the tall defensive Roman walls.  The Mithraeum, probably completely buried under the soil by this time, lay undiscovered for many centuries as London grew and changed above it.

After the Second World War, the destruction wrought on London by aerial bombardment had the side-effect of leading to the discovery of many previously unknown archaeological sites in the city.  The demolition of bomb-damaged buildings and the digging of new foundations often uncovered fragments of London’s past, similar to Christopher Wren’s observations of Roman ruins when he was overseeing the rebuilding of the city’s churches after the Great Fire of London.

In 1954 archaeologists working on a site close to the river Walbrook and Cannon Street uncovered the ruins of a small building.  It was at first suspected that it might have been the remains of an early, Roman-era church, but on the very last day of excavations a decisive discovery that revealed the true purpose of the building was made: a carved head of Mithras.

The Mithraeum’s discovery was widely covered in the media all over Britain, and when the site was opened to the public, thousands of people flocked the see the ruins, queuing around the block for their opportunity to see the remains of the temple.

Because a new, 14-storey building was to be built on the site of the Mithraeum, after a great deal of debate on the future of the Mithraeum it was decided to carefully preserve the ruins and move them to a location nearby where they could continue to be on public display.  A site was found on the corner of Queen Victoria Street, a few hundred yards from the Mithraeum’s original location, and the ruin was dismantled brick-by-brick and carefully rebuilt.  This was not seen as an ideal solution, with an article in The Times on 2nd December 1954 commenting that the structure would “lose its significance away from [its original] site.”  Although this relocation meant that the ruins were still visible, the use of modern materials in its reconstruction was criticised and for many years it was felt that the reconstruction was not an accurate representation of the ruins as they had originally been found.

When the global information company Bloomberg acquired the large site at Walbrook in 2010, hopes were raised that the Mithraeum would be able to be returned to its original location.  The demolition of the 1950s office block on the site allowed archaeologists from Museum of London Archaeology (MOLA) to further investigate the site and discover more about the Mithraeum and any other Roman structures and artefacts that might have been preserved.  Archaeologists spent almost four years at the site, between 2010 and 2014.  The ruins of the Mithraeum was carefully dismantled brick by brick, and was moved into storage while work was done to prepare its original location for the return of the stones first set in place in the 3rd Century.

Following its opening in November 2017, the Mithraeum can now be seen at its original location, several metres beneath the streets of modern London.  Further remains of the temple were discovered during archaeological work, though some of what was uncovered was too fragile to incorporate into the rebuilt temple.  Most of the fabric on display is the original Roman building, and when small areas of rebuilding were necessary specialists were employed to use materials as close as possible to what the Roman builders would have originally used.  This, along with research done during the excavations of the site between 2010 and 2014, has allowed for a more faithful and accurate rebuilding of the site than had been previously possible.

An immersive light and sound show gives the visitor some idea of the dimensions of the Mithraeum when it was in use, showing where pillars would once have stood.  A modern tauroctony, cleverly lit from above, stands where the original altars would have been.  The gloomy room recreates the low light levels of the original, cave-like temple.

Prior to the construction of the Bloomberg complex, archaeologists were also able to excavate an older incarnation of the Roman town, pre-dating the Mithraeum, which thanks to the damp Walbrook conditions had been well-preserved.  The wet ground had preserved incredibly rare items such as fragments of clothing, which usually do not survive so long.  Most precious of all, wooden tablets with traces of handwriting on them were uncovered – like the Vindolanda tablets discovered close to Hadrian’s Wall, these remarkable survivors will be able to give an insight into some of the day-to-day activities, worries and business transactions of some of the earliest Londoners.  The richness of the site excavated led to it being nicknamed the ‘Pompeii of the North’, and like the initial discovery of the Mithraeum in 1954, news of the amazing artefacts found on the Bloomberg site created a huge buzz.  In all, around 10,000 artefacts were uncovered, along with an extensive section of Roman drains and structures, including timber fences and walls.

Although a number of the wonderful artefacts found beneath the Bloomberg site – including an amazing fragment of a Roman-era door – are on display as part of the Mithraeum exhibition, they only represent a very small number of the items found there by archaeologists.  The older street excavated beneath the level of the Mithraeum is not covered in any detail the exhibition – in fairness, it is still early days since the excavations took place and many of the artefacts and structures uncovered between 2010 and 2014 are still being researched and conserved.  It is to be hoped that in time, a large and comprehensive exhibition of what was found beneath the Bloomberg complex will be opened to the public.

Although the new Mithraeum exhibition only tells a portion of the entire story of this Roman site – that of the Mithraeum itself – it gives the visitor an immersive and atmospheric glimpse into one of the more mysterious facets of life in Roman London.  Very few fragments of Londinium remain in situ and the chance to see the ruins of this place of worship on its original site is a rare and welcome opportunity to step into Roman London.

Visiting the Mithraeum is free of charge, but due to the venue’s limited capacity it is recommended that visitors book in advance via this website.

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References and further reading

London Mithraeum – Bloomberg SPACE (tickets to visit the Mithraeum can be booked via this website)

The Roman Cult of Mithras

Museum of London Archaeology Blog – “Mithras and Mithraism: top 10 things you need to know,” 11th November 2017

Kerry Wolfe – “The Ancient Roman Cult That Continues to Vex Scholars“, Atlas Obscura, 13th November 2017

‘Entire streets’ of Roman London unearthed in the City, BBC News, 9th April 2013

Museum of London Archaeology Blog – “Pompeii of the North“, 4th April 2013

Newspaper reports referenced in this article were accessed via the British Newspaper Archive and the Times Digital Archive (subscription required for both sites).