When a contractor working on the site of the new London Museum at Smithfield market knocked a tentative hole in a bricked-up basement wall, all he could see, peering in with a torch, was a muddy pile of rubble and some scurrying rats.
That unpromising beginning, however, would lead to an “unparalleled” discovery. Behind the wall, once the detritus had been carefully removed, the architects and builders were astonished to find an enormous and beautifully constructed network of subterranean brick vaults that no one, even a year into the ambitious multimillion-pound building project, had known were there at all.
There had been hints on old plans of some underground structures, “but because everything was blocked in and bricked up, we had no idea that they still existed”, said Paul Williams, the principal director of the lead architects, Stanton Williams.
Certainly nothing had suggested the sheer scale of the surviving Victorian vaults, a labyrinthine forest of carefully handbuilt arches and columns that stretch across 800 sq metres – an area bigger than three tennis courts – all hiding in one of the busiest parts of central London.