There are 3 that are publicly accessible, but an extra two exist; one for Cathederal School and one via Bishops Wordsworth School. The answer is therefore 5, but you can decide how lenient you want to be??
Sir Edward (Ted) Heath
123m (404 feet)
Odstock
Old Sarum
Salisbury Reds
There are two acceptable answers to this question! sarsen sandstone and bluestone. The large upright ring of stones are made of sandstone, but the smaller (still up to 4 tonnes!) stones are bluestone from Wales. You still only get one point if you put down both.