Roundhill Sighting Tower
This bizarre archway stands looking very alien, on the boulder-strewn heights of Ilton Moor above Roundhill Reservoir in the Nidderdale AONB that borders the Yorkshire Dales, and is the tallest thing for miles around. Conventional wisdom usually dictates that any weird, seemingly purposeless structure you find in these parts is just upper-class window dressing, but that wouldn’t be quite correct in this instance.
It’s actually a sighting tower, built in 1903 and one of three used in surveying the area for construction of an underground aqueduct to funnel water from Roundhill underneath the surrounding moorland, and output it near the small hamlet of Carlesmoor, over 5km away. I can’t seem to find much information on exactly how these kinds of towers were used, but I imagine a theodolite was mounted at the apex and then aligned with the narrow slit of a neighbouring tower to aid in triangulation, enabling the navvies to construct the subterranean channel in a straight line.
The permanence with which this trio was built is still a mystery though – I would have thought a temporary structure would be both cheaper, and easier to construct, which would be ideal as once the project is complete they become redundant anyway. These towers were built with some real solidity and not a little architectural flair though, so perhaps they were intended to become some fashion of anonymous monument, dedicated to the workers who saw the endeavour through, or alternatively, the Harrogate Corporation who oversaw construction simply had money to burn and wanted to make a statement.
A 14m tall needle-eye on the horizon will definitely do that.