Elderbush Cave is located on the SW of Thor's Crag; follow the path around from Thor's Cave to the back of the hill and look for a lone Elder Bush, SK0978 5488. The caves entrance is just below and to the side of this bush. A large round entrance leads into a single chamber, a narrow squeeze leads down from the floor to lower chambers, but you'll need a bit of caving experience to get down into them.
It's a nice enough place and nearly at the very top of the crag. Some steaming views over Ladyside.
Excavated on a serious scale by Wilson and Bramwell in the 1930's - 1950's, the cave contained 1 human burial, dated to Neolithic/Bronze Age.
Also in the cave were Neolithic and Bronze Age flint tools, and Bronze Age pottery.
Carbon dated charcoal showed the cave had been in use at least as far back as 7000BC.