Nottingham Castle

I would love to hear what the story is around this? Some sort of a natural grotto? Catacombs underneath the castle?

interesting place

It is just a crop of natural sandstone (common in this area) on which a large part of the city and its suburbs have been built. They are full of natural caves which have been used for all sorts of things over the centuries, dwelling places, beer and wine cellars, tanneries, air raid shelters during World War 2, etc. They are a tourist attraction and can be visited through an entrance from the Broadmarsh Shopping Centre. (PS I don't know why this (and other photos of Nottingham) are listed as being "1 km. from Basford", since Basford is merely a small suburb of Nottingham contained within its City limits and is not in the City Centre, where most of the Nottingham photographs are taken!)