From the outside, you’d never know the unassuming bookshop of Blackwells in Oxford, houses this huge basement.
Taken from the Blackwell website:
Constructed under the supervision of Julian Blackwell in 1966, our vast basement is the academic heart of Blackwell's Bookshop. Named after Sir Arthur Norrington, then President of Trinity College, it is quite simply one of the world's greatest rooms of books and is an essential place to see if you are visiting Oxford. It was then the world's largest single display of books in one room, with 160,000 volumes on two-and-a-half miles of shelving.