Brought into service in 1965, this power station was the first of its kind and has been copied all over the world. A work of technical ingenuity, the turbines are reversible, being used to pump water from Loch Awe to the upper reservoir on the slopes of Ben Cruachan, which in turn feeds an underground power station set deep in the mountains. The 1.5km-long tunnel leading to the machine room, which is hewn out of the rock, is also a technical feat.