Near Coelbren, Brecon Beacons, Powys

The Falls, nestled in the Brecon Beacons, are the highest in south Wales with a drop of 27 metres (89 feet). They occur at a geological fault on the river Nant Llech and are approached through a densely wooded valley.

starring Christian Bale, Michael Caine, Anne Hathaway and Joseph Gordon-Levitt was filmed at the falls in 2012.

Although the entrance to the ‘bat cave' was at Osterley Park and House, the director Christopher Nolan wanted the secret exit to be spectacular and natural. Henrhyd Falls ticks those boxes but obviously how spectacular it looks depends on the weather. The film crew couldn't risk it looking anything other than a mini Niagara Falls. It was agreed to allow them to partially dam the river for several days in order to build up a reservoir of water to unleash as the camera rolled. The National Trust worked with the Environment Agency and the Countryside Council for Wales to manage any environmental impact. It was judged to be no different from having a wet spell in the summer, hardly unheard of in Wales. There was also a ‘test day' to see if the desired effect was achievable.

The water was held back by a rig of sandbags and a timber gate to control water flow. The crew had to walk their kit down a steep footpath and construct the camera on site. On the day a diversion was placed on the footpath.

Once they were ready and Robin

(Joseph Gordon-Levitt) was in position, the command was given: further up the river, the gate was opened and a torrent of water cascaded down as if in full spate for about ten minutes. Although the waterfall was made to look as if it hid a cave entrance and exit in the film, there is in fact no cave at Henrhyd – just a hollow behind the Falls.

Usually such small scenes are shot by the ‘second unit' (a smaller-sized crew, without the main director) and the waterfall could anyway have been enhanced with a computer, but Christopher Nolan likes to do it ‘old school'.