I have compiled a list here of some of the largest data centers in the world, where the criteria for this list was to to be one of the largest data centers in their area in terms of size regarding space, servers and racks hosted. Another criteria was just the sheer coolness of the building hosting the data. Enjoy:

Microsoft’s Quincy Washington Data Center

The Tokyo Data Center

NJ2 in Weehawken, N.J.

IBM Green Data Center

HDS Yokohama Green Data Center

Microsoft’s Chicago Data Center

Worldwide LHC Computing Grid

NGD Europe

Lakeside Technology Centre

 Global Switch (Largest in Southern Hemisphere)