Free HDRI Images / Backplates / Backgrounds

 We've put together a few good links to free HDRI resources around the net. Many of these are great for testing out HDRI processes or your rendering setup. For more professional results you may wish to move up to professional HDRI backplates, such as the Dosche HDRI images.

Free outdoor HDRI (US)

Selection of Exterior HDRI,
Futuristic HDRI 
Exterior & Buildings HDRI
courtesy of Smashmethod, DeviantArt

Vienna HDRI, Exterior & Interior

HDRI explained, including Rome exterior images & interior HDRI

Interior & Exterior HDRI from Leuven, Belgium