Magdeburg, Germany, is the place where you can visit and admire the Open Air Library.
"With no need for registration, the public library gathers readers in a contemporary outdoor setting. Readers can take books and bring them back or bring other ones in exchange, so that everyone can enjoy this open place and the knowledge it brings. Open 24 hours a day, the Open Air Library is also used for public readings, local band concerts and other cultural events. The elementary school uses the library for theater plays and every community member can take part in this cultural experiment."
Via Doug Mirams