For these to work you need to slowly start crossing your eyes until you see three images, if you see 4, get the middle two to join together- if you do it right the middle image will seemingly lock in place and will be in clear 3d!
Check out these ones too:
Chicago Skyline at night
Ariel photo of Chigago during the day
Long hallway
Franklin Bridge from above
Statue in Lincoln Park
For more photographs of this type, Google image search for "Cross eye 3d" or "Side by side 3d".
For a better tutorial on how to view have a look here
