St Peter's Seminary, Cardross, near Glasgow, was built by architects Gillepie, Kidd and Coia in 1966. It is a Brutalist structure of "world significance", that was abandoned by the church in the 1980. It briefly served as a drug rehabilitation centre before a fire left it in the ruinous condition you can see in these photos I've swiped from Wiki.
Here is a rather wonderful video in which film maker Luke Alexander has used old footage from Murray Grigor's "Sound and Light" film about St Peter's in it's heyday from 1972, and combined it with contemporary footage of it's post-apocalypse shell.
It's a site rich in hauntological references and possibilities I've been keen to visit for many years and occasionally dream about.