“….The mystery of where a 100 metre medieval tunnel in Scotland ends has finally been solved thanks to recent excavations.
“….The intricate underground passageway next to Paisley Abbey in Renfrewshire is believed to have been a [14th century] drainage system but has been puzzling people for decades because no one could figure out where the exit was.
“….’Often these types of drains are in rural areas not urban ones where there will have been pressure on the land above it – but considering the amount of buildings on that site over the centuries, the condition of the drain is quite incredible.’
“….The find is now being covered up again but it could lead to a more permanent visitor attraction with access to the drain in the future….”
To read more, go to this article.
PS: The above url also has the following at the end! Tantalising. A couple more known generally than others.