Isambard Kingdom Brunel is one of Britain's greatest-ever engineers. His first project was the Rotherhithe Shaft, the starting point for London's Thames Tunnel. The tunnel was the first in the world known to be built underneath a river and the shaft is now set to become a theater.

The Thames Tunnel was designed to allow horses to move loaded carts across the River Thames (although it was never ultimately used for this purpose). With masts up to 100 ft (30 m) tall needing clearance on the river and horses needing a gentle enough gradient in order to be able to pull their carts, a bridge would have needed to be too large to be practical.

Designed by Brunel's father, Marc, work on the Thames Tunnel began in 1825. When it was completed in 1843, it became a major tourist attraction, with millions of people paying to walk through it. In order to build the tunnel, though, access was needed to a point where the tunneling could start.

For this, a shaft was to be built on the south side of the Thames in Rotherhithe. Rather than follow the typical approach of repeatedly digging down and then underpinning the sides, however, the Brunel Museum explains that Marc Brunel had the idea of building a brick tower on the riverbank and simply letting it sink into the soft ground under its own weight, saving both time and money.

Today the shaft remains sealed from the public, but the museum, which is located nearby within the Thames Tunnel Engine House, has taken a lease out on the Grade II-listed structure. The organization plans to reanimate the 50 ft (15 m) wide by 65 ft (20 m) deep space as an underground performance venue that will host events and shows.

Project architects Tate Harmer describe the venue as having "smoke-blackened brick walls from steam trains" that provide "a raw but atmospheric backdrop." The firm says that the project will employ a ship-in-a-bottle approach that will limit construction access to a newly-created public entrance. Amongst the additions to the space will be a freestanding cantilevered staircase aimed at giving visitors impressive views of the historical space.

Work on the Rotherhithe Shaft is expected to begin in October of this year and to be completed by January 2016.

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