Bona Lighthouse

Okay, it doesn't look much like a lighthouse, but it once was. It was built at the north eastern end of Loch Ness by Thomas Telford as part of the Caledonian Canal project. Initially it was a dwelling house  with stores, but the octagonal turret was also designed as a lookout point. In 1848, some thirty years after the completion of the canal, a light was installed on the upper floor, and it became a lighthouse. Seemingly Telford used this  design in Shropshire and near Holyhead as well. (You can tell I've read up about this, can't you?) The extra shot gives you a bit more context.