An 800-year-old London church tower is floating 45ft off the ground – here’s why

Central London is no stranger to ambitious construction projects – but this is a ‘never seen before feat of engineering’.

Several buildings at 50 Fenchurch Street have been demolished to make way for a 36-storey office block right in the heart of the city.

But there were two listed constructions on the site which needed to be preserved – and how do you protect these while also excavating below ground level to construct a four-storey basement?

The answer has led to the All Hallows Staining tower, the remains of a Grade I listed 800-year-old church, standing on a podium 45ft up in the air.

That podium is actually at ground level, however, with a recently-finished ‘bottoming out’ process removing more than 125,000tonnes of earth below the tower to clear the way for construction.

Until now, the church tower as well as Grade II listed Lambe’s Chapel Crypt were inaccessible due to their location on private land.

But the new development at Fenchurch Street will include a new ‘public realm’, creating green space and eventually allowing the public access to both listed buildings.

While the bulk of the development reaches 36 storeys, there is a 10-storey section with a public roof terrace located behind where the church tower will be located.

It’s hoped the construction project will be complete by 2028.

How workers suspended a medieval tower 45ft in the air

But how do you suspend an 800-year-old tower in the air without the whole thing collapsing?

Metro spoke to Robert Samuel, UK head of development at AXA IM Alts, the company behind the development.

He explained how, at the start of the project when figuring out how to protect the church tower, the developers held a ‘competition’ of sorts to come up with the best solution.

Robert told Metro: ‘In really simple terms, it had to stay exactly where it is. It hasn’t moved more than a few millimeters.

‘It had its own ancient foundations, and work has been done to the tower probably every century over the last 700 years.

‘We had to build a raft underneath it piece by piece, because if we tried to dig underneath the whole thing, you would get movement, so we had to build a new set of raft foundation, the same way a beer mat would sit under a pint glass.

‘But we had to do that in 26 little pieces, in order that it didn’t move.

‘Before we did that, we put the stilts in the ground, and then built the foundations underneath the tower, which was then eventually connected to the stilts that you see in the photos now.

‘We then very carefully, bit by bit, dug out underneath it. And it’s not going anywhere, it’s very happy.’

Robert and the rest of the development team have worked closely with archaeologists and the Museum of London – an inevitability when building in the City which has centuries of history just below ground level.

So far during the excavation developers have come across a Victorian-era bone comb, a halfpenny from Edward I’s reign, and pieces of Roman-era mosaics.

The tower is monitored 24/7 to ensure it doesn’t move, but the team are confident that it will stay safe even while construction work goes on around it.

Plus, the church tower is considered something of a ‘survivor’, with many of its original surroundings (including the rest of the church building) destroyed in the Great Fire of London in 1666, and more damaged during the Blitz in World War II.

‘As a developer to a very large project team, we have some of the best engineers in the UK, and we set a challenge,’ Robert explained to Metro.

‘One solution could have been to try and pick the whole thing up and move it, but presented with that challenge they actually came up with this alternative.

‘Moving a building is a vast exercise, you would end up building a sort of cage around it and then still put some form of platform underneath it to be able to move it.

‘In doing that there’s likely more intervention to the structure itself which then has to be repaired.

‘This is the least invasive way of doing it, and actually a very efficient way of doing it because it doesn’t have to be moved to another location and moved back.’

On top of the challenge of protecting a Grade I listed structure, the developers at Fenchurch Street also have to deal with the same issues all City of London construction sites face – a lack of space.

Robert explained: ‘Building in any city, but particularly in the City of London, you have a limited amount of space to do anything, not much elbow room.

‘It’s coordinating all of those activities, all these things that need to happen at the same time, which the wider team have done phenomenally well.

‘Both us as developers plus the city, generally everyone’s fond of that juxtaposition of new and old and how they sit together and it tells a wonderful story of the history of the City of London.

‘It’s pretty much guaranteed anywhere you dig in the square mile, you’re going to come across something.

‘The Museum of London provide services and expertise in understanding how to excavate things and record the findings, and then they are either brought back to site for us to be able to display, or they’re with the museum to display and archive.’

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