London hides one of its most remarkable archaeological treasures beneath 101 Lower Thames Street, a thoroughly unremarkable 1960s office building in the Square Mile.
The site is an 1,800-year-old private Roman house, complete with a bathhouse that once sat in its garden, surviving against considerable odds.
It was the genius of City of London Surveyor James Bunning that ensured the remains were preserved at a time when Roman discoveries were routinely destroyed or even blown up.
The bathhouse was first uncovered in February 1848 during excavation work on the grand London Coal Exchange, one of the most important business locations in the capital.
The Coal Exchange was where coal taxes were levied and trading carried out, with those taxes having already funded much of the rebuilding of London after the Great Fire of 1666.
Coal tax would also go on to fund the massive Victorian works of the Thames Embankment, the Bazalgette sewers, and the Holborn Viaduct, making the Exchange a site of enormous civic significance.
The opening of the Coal Exchange was a huge affair, with hundreds of thousands attending in the hope of seeing Queen Victoria herself.
Unfortunately the heavily pregnant Queen caught chicken pox and was forced to stay at home, but Prince Albert and the nine-year-old heir George came instead, the first time George had been presented in public.
Bunning insisted on preserving the Roman discovery, and underneath the Exchange, visitors could descend an iron staircase on application to the beadle and view the bathhouse remains directly.
Fast forward to the early 1960s and traffic demands meant the road had to be widened, and despite massive protests led by John Betjeman and the Victorian Society, the Coal Exchange was demolished.
City of London Archaeologist Peter Marsden accessed the building works and found evidence of even more Roman remains, successfully appealing to the authorities to halt further destruction.
His team managed to unearth an entire Roman house surrounding the bath section, revealing a structure built in the late second century and occupied almost to the end of the Roman period.
A coin hoard found at the site confirmed the house was used right through to the final years of Roman occupation, providing archaeologists with a vivid snapshot of domestic life.
The bathhouse itself was constructed roughly fifty years after the main building, positioned in the middle of what would have been the garden, with a view of the river beyond.
Nobody knows for certain why it was built there, and theories suggest it might have been a tavern or inn for travellers, which remains one of the enduring mysteries of the site.
It is the only Roman house accessible to the public anywhere in London today and is preserved as if it were an active archaeological dig, complete with hypocausts and a three-room bathhouse.
Visitors find it a startling contrast to the nearby Mithraeum, which offers a very curated and theatrical experience, whereas this site delivers raw, unfiltered archaeology in its most honest form.
The site is open for public tours given by the City of London Guides on Saturdays from April to November each year, with details available on the City of London website.