HM Prison —, high security detention centre situated at RAF Long Kesh, Northern Ireland, from 1971-2000 (4)
I believe the answer is:
maze
(Other definitions for maze that I've seen before include "Puzzling network of paths" , "It's easy to get lost in one" , "there's no obvious exit from this" , "Labyrinth of paths and hedges to get lost in" , "confusion" .)