As the Museum of London formulates plans for its £250m (US$324m, €291m) move to the iconic Smithfield Market, its exhibition team is digging deep to present London’s history in new ways – including opening up the site's underground passages for a glimpse of what the city was like in Victorian times.

The museum was given the green light to move to its new home in January 2016, after alternative redevelopment plans for Smithfield were abandoned. It will retain many of the Victorian-era buildings on the site, incorporating them into the museum’s design and, in some cases, its exhibitions.

The Smithfield complex dates back more than 800 years, with a livestock market occupying the site as early as the 10th century. It has existed in its current guise since 1866 and still operates today as London’s only major wholesale market.

In their exploration of the site, museum officials discovered some interesting features in the building’s underground tunnels, which could be used as a live representation of London’s history.

One of the key findings was that Thameslink trains between Farringdon and City Thameslink travel beneath Smithfield market, and that the line is accessible from the building’s lower levels.

“When we discovered more about the building, we found that the trains actually pass through the basement of the building,” said Alex Werner, lead curator for the Museum of London, speaking to Attractions Management.

“It’s not completely shut off when you go down there. You can actually see the trains passing through the site. Being a museum, the idea that we could create some kind of spectacular space which allows us to give an interpretation of what you’re seeing, as well as the possibility of people passing in the train actually looking into the museum, is very exciting.”

The railway line dates back to the 19th century, when it was used to transport meat to Smithfield, with products then brought to the surface using hydraulic lifts.

The museum has a vision, currently in the planning phase, to make the train tunnel running through the building see-through – creating a unique real-life exhibit telling the story of Smithfield.

“Occupying the westernmost portion of Smithfield Market, the railway lines that run under there came in the 1880s and 1890s,” said Werner. “You have to imagine this sort of cavernous, underground world in the Smithfield area. The average passer-by would have no concept of this hidden landscape beneath London.”

Another unique discovery was the emergence of the “lost” River Fleet – one of a series of canals and rivers buried beneath London’s streets more than 150 years ago.

The Fleet, which runs off of the River Thames, flows beneath the Smithfield site and was uncovered in the building’s depths. Eventually incorporated into a sewer system following the Great Stink of 1858, the Fleet was once a broad tidal basin several hundred feet wide at its entrance. It also acted as a water supply for the market.

Still at an early stage of planning, the museum wants to incorporate viewpoints of the underground river into its design.

“At one side of the basement site, you’ve got the line where the river runs,” said Werner. “It’s one of London’s lost rivers covered over in the 19th century. It was converted into a glorified sewer but it’s still there. It runs quite close to the westernmost edge of the museum site. We’re exploring at the moment how to link that up and having a viewing point onto the Victorian-era sewers. The story is such a compelling one – the year of the great stink and the building of the sewers – saving London when it was on the brink of disaster.”

According to Werner, the potential of London’s underground is massive, with the hidden history drawing public interest and more history yet to be discovered.

“We’re exploring. We haven’t found everything,” he said. “There are a number of tunnels that have become disused or blocked up. We’ll have to interpret the paths that they used to run because a lot are no longer there. You can still make out the features though and the structure of the general market building is there.

“You have to dig a bit deeper but it gives us the chance to unlock some lost history. It’s one central London’s last hidden spaces. I think this underground world has really captured the public’s imagination. It’s a challenge in terms of presenting as an exhibition because how do you create these galleries? You have to link it in some way to the Victorian era city. That’s the period all this happened. This was when London was the world’s largest and most powerful city. These reasons are sort of technological achievements of the age and they were putting things you see in practice today back then.”

The museum announced plans to relocate in March 2015, with management citing a number of problems at its current site including poor accessibility, an ageing building and a poor location. Stanton Williams and Asif Khan are the project architects. The new site is scheduled to open in 2022.

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