A hidden Victorian chamber beneath Tower Bridge is opening to the public this weekend

Nothing beats cruising over Tower Bridge on the top front seat of a double-decker, or watching it crank open like the jaws of a whale over the Thames. You can even pack in a yoga sesh on its 42-metre glass walkway if you fancy. As bridges go, it’s one of the best.

But the most interesting part of this awesome metal structure is actually what lies beneath: a subterranean Victorian chamber.

The Bascule Chamber was built to make room for the huge counterweights or ‘bascules’ (French for balance scales) that move below ground as the bridge is opened, and the space is rarely open to the public. But something’s stirring this week: the doors are about to be unlocked. The Guildhall School, the City of London Police Museum, the London Metropolitan Archives and Tower Bridge have been busy working together on ‘Blackout’, an immersive video projection and sound installation which tells the story of a post-Blitz London. 

‘Blackout’ takes its inspiration from the photographs of two policemen, Arthur Cross and Fred Tibbs, who captured the destruction across the City and Tower Bridge when the bombs hit. The hour-long performance aims to evoke the impact of this attack on the bridge, using the underground arena as its stage. Now is your chance to visit London’s very own chamber of secrets. 

If that's given you a craving for chambers don't miss London's other secret subterranean wonders: 

Brunel Museum Shaft

Look out for underfoot film screenings, concerts and plays in Brunel’s tunnel below the Thames.
Brunel Museum. Rotherhithe Overground. Dates and prices vary.

Churchill War Rooms

Walk in the footsteps of Gary Oldman (and Winston Churchill) at a bunker beneath Westminster.
Churchill War Rooms. Westminster.  Open daily. £18.90, £9.45-£15.10 concs.

Clapham South – Subterranean Shelter

Descend 180 steps below ground level to explore this Blitz-era shelter. 
SW12 9DU. Clapham South. Various dates with Hidden London tours. £41.50.

The Bascule Chamber Concert 'Blackout' will take place in the Tower Bridge Bascule Chamber between Fri Mar 23 and Sun Mar 25. Standard adult tickets are £28.50, concessions £19.50. The nearest tube is Tower Hill.

Not ready to emerge above ground? Check out London's hidden subterranean Mail Rail. 

Find more wonderful things to do in London this month.