I think it might have been that one
It was the Pont Cysyllte aqueduct, we posted about a few years ago, April identified when I posted about a walk which featured some secret steps, a falling tree and a mad local accountant, who had uncontrollable urges with a chainsaw. It is an interesting place to go for a walks. If you go the and come back being able to pronounce Froncysyllte so that the locals recognise it, one of the pronunciation great stepping stones. I have the horrible feeling that the nearby householder will have buried the Secret Steps under his garden rubbish, it led into an awesome way down though the quarries that provided the stone for the aqueduct.