Big Butts, Rochdale

'Big Butts' is located on the River Roch, which runs beneath Rochdale's town centre and is a tributary of the River Irwell. Most of the river has been covered since the early 1900s, flowing underground for about 450 metres through a mix of stone and spraycrete, a newer protective material. One bridge from the 14th century still stands as a rare example of medieval engineering. Along the culvert, there's a Victorian egg-shaped sewer that connects to a processing facility.

Plans are underway to spend around £3.5 million to uncover sections of the river and reveal the medieval bridge again. Locals seemed interested when they saw two men in waders entering the river. I think most people wouldn't have questioned us if we had fishing rods. Drunk passers-by stopped to take pictures and chat about what we were doing. The river had low flow due to the dry weather, and the depth stayed consistent through the culvert.