When I was studying archaeology at Glasgow a few years ago, the commercial arm of the department (GUARD) were contracted by the council to do some geophysical surveys of the Green to determine whether anything remained underground that they should be aware of, particularly with regards to WWII air raid shelters.
The results were quite interesting, as they not only produced fairly clear plans of the shelters, but also discovered the infilled remains of a swimming pool, started in 1939 but never finished.
The results, including plans of the shelters, can be found here:
http://www.guard.arts.gla.ac.uk/804/804_front.htm
Gary