The Livraria Lello is one of the most impressive book shops in the world. Not because of its collection of books, but because of its design.
Located in Porto Portugal, the store was opened in 1904 and designed by Francisco Xavier Esteves.
The store has been so popular that they charge admission. That can go towards the price of a book if you decide to actually purchase something.
As with many European sites that are popular with tourists, it is recommended to go there outside of peak holiday seasons.