London Mithraeum: Reimagining the famous Roman temple

12 mins read
The new reconstruction of the London Mithraeum reimagines the temple structure, immersing the visitor in Roman Britain. (PHOTO: James Newton)
On 14 November, London’s Temple of Mithras – now known as the ‘London Mithraeum’ – reopened to the public as the first new interpretation of a Roman ruin in the capital for nearly 20 years. Sophie Jackson, the lead archaeologist on the project, reports on the temple’s 63-year journey from its initial discovery in 1954 to its recent reconstruction and installation on the site of Bloomberg’s European headquarters.

After you descend the darkened stairs and pass through an entryway, lights illuminate the room and you are presented with the ghostly outline of an atmospheric temple, with the physical ruins of its foundations below. Through judicious use of light, shadows, and sound, the new reconstruction of the Temple of Mithras transports visitors back into Roman London. But the structure did not always have such a lavish and immersive presentation. It took a collaborative team drawn from across two continents, and involving everyone from archaeologists and historians to stonemasons and light artists, to restore and reimagine the temple, bringing it back to some of its former grandeur.


The ruins of the mid-3rd century temple were first uncovered in September 1954, during excavations of a Second World War bombing site prior to the construction of a new office building. Back in 1952, a fragment of the Roman building had been recorded in an exploratory trench by archaeologist William Grimes, and he had marked the site for further investigation. It was only after a sculpted marble head was discovered on the last day of the dig, however, that the function of the building was confirmed as a temple to the cult-god Mithras. A three-week extension allowed more of the temple to be excavated and an incredible cache of Roman sculpture to be recovered. These statues, now in the Museum of London, had been buried beneath the floor of the temple in the early 4th century.

The temple was first uncovered in 1954, though archaeologist William Grimes had discovered evidence for it during an exploratory dig two years earlier.

There was a frenzy of press and public interest in those few weeks, with tens of thousands of people visiting, famously queuing for hours on the surrounding streets (see CA 296 and CA 303). Debate raged in the media and in government about what to do with the temple remains: save it for posterity and ask the developers to redesign their building, or allow it to be removed and rely on archaeological records and photographs for future study? The site’s owners, Legenland, defused the situation by agreeing to dismantle the ruin at their own cost, store the salvaged materials until the office building was finished, and then reconstruct the temple in a more convenient location on the site.

In February 1962, the reconstruction was unveiled to the public. It was approximately 100m from its original location, orientated north to south instead of east to west, and raised above the ground. This was in stark contrast to the original temple, which was partly subterranean – an allusion to the mythical cave in which Mithras was said to have killed the primordial bull.

The temple was inauthentically reconstructed in the 1960s; exposed to the elements, it quickly became moss-grown. (IMAGE: MOLA)

There were other inaccuracies: the floor surface consisted of outlandish paving and much of the architectural detail was left out. Worst of all, the reconstruction was built with very hard cement mortar and, as some of the salvaged material had been pilfered in the years following 1954, the builders had to supplement the original piles of roughly hewn Kentish ragstone with ‘other stone from elsewhere’. Grimes was not consulted about the reconstruction and he dismissed the result as ‘virtually meaningless’ as a representation of the temple.


Despite being inaccurate, the 1960s reconstruction was probably visited by more tourist groups than any other Roman ‘monument’ in London – partly because it was just off the street frontage and visible at all hours, and also because it was all that was left of what was originally one of the most complete mithraea ever excavated in northern Europe. It was mentioned in most London guidebooks and even had a bus stop named after it. In 2007, English Heritage (now Historic England) gave it protected status, and added it to the national list of historic buildings and structures owing to its significance as an example of early conservation, and because it contained material from the original temple.

The 1962 reconstruction was carefully dismantled, stone by stone, using diamond-tipped chainsaws. (PHOTO: MOLA)

In 2010, the financial information company Bloomberg bought the site for their new European headquarters, and one of the conditions for redevelopment of the 1.2ha site was that the temple remains should be reimagined. The brief from the City of London (the Local Planning Authority responsible for the site) asked that the 1962 version be recorded, dismantled, the materials put into store, and then reconstructed as close as possible to the location of the original Roman structure. Information on the discovery and history of Roman Mithraism was also to be provided, and the new reconstruction should ‘evoke the experience of being in a mithraeum’.

The Bloomberg excavations uncovered more than 14,000 artefacts (see CA 280). Finds included many personal items, including this bull plaque. Many of these items are now on display at London Mithraeum. (IMAGE: MOLA)

MOLA had already been investigating the Temple of Mithras and issues relevant to its potential relocation and display. One of the first philosophical discussions to take place was about whether it was appropriate to re-reconstruct the temple, as there were few precedents and examples of best practice for the treatment of a ruin that has already been altered and moved. As these were not in situ remains, however, it actually provided a great opportunity to be more creative with the interpretation. The design team agreed that if the ‘ruin’ was clearly announced as a reconstruction, it would be better in terms of the educational value and visitor experience to present the structure as it was on the last day of excavation in 1954, which would be the closest it was possible to could get to the earliest phase of the temple – albeit with the scars of its later history.

This amber gladiator helmet amulet was also discovered during the excavations. (IMAGE: MOLA)

While discussions were taking place about what to reconstruct, the team was also investigating how to take the 1962 reconstruction apart without destroying the surviving masonry and Roman brick. Normal hand tools bounced off the hard cement mortar, and it looked at one point that it would be impossible to salvage much material intact. But a successful method was eventually found and, in 2012, with the relevant consents in place, it was possible for the structure to be dismantled using diamond-tipped chainsaws to saw through the hard cement mortar joints. Although almost all the original Roman material was recovered intact, it was clear at this stage that there was not enough stone and brick left to build a full reconstruction. In order to work out how much extra was needed, the MOLA team had to create construction drawings from which masons could build the new temple ruin.


The tauroctony sculpture, depicting Mithras slaughtering the primordial bull, was the focal point of most mithraea. (PHOTO: James Newton)

Mithras was a Roman deity who first appeared in the 1st century AD, and was often associated with Sol, the sun god. The traditional image of Mithras is as a young man, wearing a soft Persian-style cap and clothing, killing the primordial bull in a cave while surrounded by other figures and animals. The meaning of this scene is open to interpretation, but it is likely to represent an act of creation and fertility, with references to the constellations and the cosmos. Often referred to as ‘the tauroctony’, this bull-slaying imagery is found in most mithraic temples.

Mithraism was a mystery cult, popular with soldiers and merchants. It had a serious spiritual side, but it also provided a social network for men who travelled widely across the empire. There were seven grades within the cult and the leader was known as the Pater, or father. Evidence exists for initiation ceremonies into the different grades, but the rituals and beliefs of the cult were kept secret, so what we do know comes from archaeology, inscriptions, and some later – mostly hostile – written accounts.

This artistic reconstructions by Judith Dobie depict what the interior of the Temple of Mithras may have looked like. (IMAGE: MOLA/Judith Dobie)

The temples – which are located throughout the Roman Empire: the remains of another such structure can be seen at Carrawburgh fort on Hadrian’s Wall, for example – were thought to represent the cave in which Mithras killed the bull: windowless, dark, and often partly sunken. The London Temple of Mithras was stereotypical in this regard, but was relatively large compared to other mithraea, measuring roughly 18m long by 8m wide. It was divided into two side aisles and a central nave, and it is thought that it could have accommodated roughly 30 cult members, most of whom would have sat on wooden benches in the side aisles. Rituals most likely took place in the nave and at the altars near the cult statue at the west end of the building. One of the distinctive features of this temple was the seven pairs of columns running down the centre of the structure, presumably corresponding to the grades in the cult.

The London temple was first constructed around AD 240-250. It then underwent several modifications, before a major rebuild in the early 4th century, when the columns were taken out and the sculptures associated with Mithras were buried beneath the floor. The structure continued in use until about AD 380, before being abandoned.

In recent excavations for the new Bloomberg building, fragments of the foundations of the eastern third of the temple were found to survive, as well as an entrance lobby, or narthex, which may have been where worshippers prepared themselves for the rituals. Remains of surrounding buildings and structures were also found, creating a new picture of the landscape within which the temple was originally built. It is now thought that the temple was set in the grounds of a large house, perhaps belonging to Ulpius Silvanus, a veteran of the Second Augustan Legion, whose name is inscribed on one of the key cult images from the temple.

This artistic reconstructions by Judith Dobie depict what
the exterior of the Temple of Mithras may have looked like. (IMAGE: MOLA/Judith Dobie)


Archaeologists are expert at taking structures and remains apart, recording, and removing them. It is another thing altogether to rebuild a monument using archaeological records and photographs. William Grimes and his site director Audrey Williams produced some of the best excavation records that could be hoped for: accurate, detailed, and comprehensive, they were accompanied by hundreds of photographs, newsreel footage, and even a Ministry of Works model from 1955. Even so, it took many visits to the archive and advice from Dr John Shepherd, Grimes’ research assistant in the 1980s and an expert on the London Temple of Mithras, to get to a point where we could even count how many extra bricks and how much new stone was needed.

The team had to sort through hundreds of original stones. (PHOTO: PAYE/MOLA)

In 2016, as we neared the date for reconstruction, the stonemasons PAYE Conservation were commissioned to build the new structure. They began sorting the salvaged stone in a warehouse in Woolwich, sourced ‘new’ ragstone from the last quarry in Kent, and had new bricks hand-made from clay dredged from the Humber estuary. All of this new material was marked to make sure it could be identified in future. As the original building was partially rendered, it was decided only to use the new stone in these areas, allowing visitors to see ‘just’ original stone and mostly original brick.

Different dry mixes of hydraulic lime mortars and renders were prepared, based on samples taken from other 2nd- and 3rd-century Roman buildings in London, and new oak was treated to look like the waterlogged surviving timbers that Grimes had recorded within the temple.

Stone conservators carefully reconstructed the temple, following the original specifications as closely as possible. (PHOTO: PAYE/MOLA)

One of the often-quoted failings of the 1960s reconstruction was the use of paving for a Roman floor. We felt that we absolutely had to get this right, but it was surprisingly difficult. The first floor of the temple would have probably been timber boards laid on earth, but only the tiniest fragments had survived. We thought that it would be best to recreate the earth surface that Grimes and his team exposed in 1954, instead. Although we had kept hundreds of buckets of soil from the Bloomberg dig for this purpose, we could not use this ‘real’ earth as it was not stable enough. So the dirt floor that visitors actually see is a hand-painted resin cast of authentic Roman soil. The earth was meticulously laid out and trampled before being cast, in order to achieve an accurate representation of how the ground would have looked during the original excavation.

One of the other practical challenges for the project was where to put the new reconstruction. The brief was clear: it should be as close as possible to its original position and at original Roman ground level, approximately 7m below the modern ground. When MOLA archaeologists unexpectedly found some fragile remains of the original temple in situ, though, it was clear that the new reconstruction would have to be shifted slightly to the west of the original site to allow these nationally significant archaeological remains to be preserved.

To recreate the temple’s mud floor, Roman soil was laid out, trampled, and then a hand-painted resin cast was made from it. (PHOTO: PAYE)

The other key part of the design process was working out how to make this ruin atmospheric and evoke the feeling of being in a real mithraeum. The brief for the design was to create a memorable, powerful, and authentic experience. A mini-competition was held in 2013, with the New York-based design company Local Projects winning the commission. Their proposal was to put all didactic content in the spaces that visitors see before coming into the temple display, and then to create an atmosphere that gives visitors space to use their imagination. Local Projects’ leader, Jake Barton, has quoted Christopher Woodward’s In Ruins: A journey through history, art, and literature as an inspiration: ‘A ruin is an incomplete dialogue between an incomplete reality and the imagination of the spectator’.

Local Projects worked with light artist Matthew Schreiber to create walls and columns of light that could fade in and out to an appropriate soundtrack. Light was thought to be the best medium for creating an impression of the superstructure of the original building, particularly as scholars think that mithraic rituals used dramatic lighting; Mithras is sometimes associated with Sol, the sun god, and lighting props have been found at other temple sites, most likely used to create moments of mystery and dramatic effects.

Putting the final touches to the temple. The new reconstruction was completed in summer 2016 and the display was in place by autumn 2017 – ready to open to the public on 14 November. (PHOTO: MOLA)

The sound effects were harder to pin down. As no one really knows what went on in a mithraeum, the design team relied on expert advice from a panel of Roman scholars to create the sounds of religious rituals and initiations, as well as the feasting and drinking that appear to have accompanied these rites. Some of the ‘script’ was taken from graffiti on the walls of a mithraeum discovered beneath the church of Santa Prisca in Rome.

With most of the pieces in place and the details ironed out, construction work started in spring 2016, and the temple reconstruction was completed that summer. The remainder of the display was in place by autumn 2017.


London Mithraeum is no ordinary presentation of archaeological remains. The unique circumstances of this twice reconstructed and relocated ruin allow for an immersive and powerful reimagining of the Temple of Mithras, designed to help visitors connect with London’s Roman past.

The temple reconstruction is the centrepiece of the London Mithraeum exhibition, but there are four other components to the whole space. At ground level, there is an art gallery showcasing the work of contemporary artists responding to the history of the site and area; currently showing is an amazing tapestry and sculpture by Isabel Nolan, inspired in part by Grimes’ archaeological drawings.

In one corner of the art space is the portal into the London Mithraeum, marked by a massive case containing over 600 artefacts found during the excavations for the Bloomberg building, including several Roman wax writing tablets (see CA 317); electronic tablets are on hand to provide information about these finds. A staircase or lift takes visitors down to the mezzanine level. Carved into the black granite of the stairs is an archaeological section drawing identifying the actual ground levels recorded in this area. By the time you get to the mezzanine, about 5m below the modern ground level, you are in the early 5th century, at the end of the Roman occupation of Britain. An atmospheric introduction to Mithras and the London temple prepares visitors for the immersive London Mithraeum experience, before they descend further into the actual temple ruins.

The mezzanine level of the exhibition provides information about the temple and Mithraism through interactive kiosks, before the visitor descends further into the temple itself. (PHOTO: James Newton)

London Mithraeum Bloomberg SPACE is really a new cultural attraction in the City of London. There are (nonchain) restaurants around the groundfloor level of the building, and public art installations and spaces that reflect the site’s history, including amazing pools with cast-bronze river beds – a reference to the lost Walbrook river that once ran across this site – by artist Christina Iglesias, and the reinstated routes of Roman and medieval roads that once crossed the site.

Above all, this is a space where Londoners and visitors can let their imaginations run: envisioning the people who visited the temple 1,800 years ago and the rituals they took part in, and perhaps reflecting on the role these people played in the development of London.

This feature appeared in CA 334.

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