"Τα βιβλία είναι στη βιβλιοθήκη."

[LukasGroth]

German Bibliothek, French bibliothèque, Italian/Spanish/Portuguese biblioteca, Polish biblioteka, Russian библиотека, ...

Libraries are a Greek thing in many languages. ;)

[em7ec]

How would one distinguish a library and a bookshelf?

[enamrouy]

Or book case?

[AndyPyrope]

They mean a slightly different thing but they are used almost interchangeably nowadays, at least according to what I've read.

[AnCatDubh]

Yeah but dónde está la biblioteca?