Has a system designed to remove poisonous gases ever looked so graceful as the one at Rookhope?
Like a forgotten doorway to another world, this small ruin has become an icon for the village of Rookhope. At Lintzgarth, just up the valley, the Rookhope Arch is one of few remnants of a two-mile flue that ran horizontally over the ground rising into the high moors, carrying poisonous gases from the village’s lead-smelting works.
In the early 1800s, all the major smelt mills of the North Pennines had such contraptions, releasing their fumes into the air above the fells.
There are better survivors at Ramshaw and Allendale, but Rookhope’s solitary arch — part of a six-arch viaduct for the chimney — has a charm of its own.
See more of Secret Britain
Burrow Mump, Somerset: Alfred the Great’s lookout point
The famed hill in Burrowbridge is today's Secret Britain spot.
Traeth Llyfn beach, Pembrokeshire: ‘A beach so remote you’ll be the sole person on it’
The remote Traeth Llyfn beach is a Secret Britain spot accessible only by the adventurous.
Coombe Hill, Buckinghamshire: ‘Rare chalk grassland humming with butterflies, wildflowers and grazing cattle’
The view from Coombe Hill, Buckinghamshire, is Friday's Secret Britain selection.
North Meadow, Cricklade: An ancient field where half a million wildflowers create a wall of colour
The spectacular North Meadow, in Cricklade, Wiltshire, is a Secret Britain sight we should all enjoy at least once.