The Colsterdale Towers: The rare Grade II-listed structures which overlook Yorkshire moors

Prior to their construction, a set of four sighting towers was built around Colsterdale and on nearby moors.

These were erected to conduct surveys, especially for the construction of an aqueduct through which water would be conveyed southwards to Harrogate.

The one which looms over both reservoirs and is situated above Arnagill Crags is the Ilton Moor tower. The most photographed of the towers, it stands 46ft tall (14m).

Work commenced in 1905, planning permission having been granted two years earlier, and tunnelling work for the aqueduct took several more years. It wasn’t until 1911 that water finally began flowing to Harrogate’s taps.

The town’s water corporation was permitted by parliament to take no more than four million gallons per day. The rest of the water had to flow onwards to Leeds.

Another tower, known as Carle Tower, is slightly lower and stands above Wandley Gill on Kirkby Malzeard Moor. A third, Carlesmoor Sighting Tower, stands next to a small village of that name below Stock Beck Moor. A fourth tower was built from timber and has long since disappeared.

The sighting towers are now Grade II-listed structures.

According to English Heritage, because such survey towers became redundant once their associated engineering projects had been completed, very few of them have survived.

The tower on Ilton Moor is said to be of special interest “as a rare form of structure with an unusually distinctive design”.