Heh. That was the alternate title for this post at the nonist.

Personally, I've worked in three of the libraries pictured -- The Rijksmuseum, the Handelingenkamer, and the British Library -- although the picture for the British Library is actually from the old building (now the British Museum), not the new. I've only worked in the new building.

Apart from these, some of my personal favorites are the Wren Library at Trinity College, Cambridge, the Bodleian, at Oxford, and the John Rylands Library - Deansgate, in Manchester.