Depends on the photo. I had a photo that shows military unit marching between two of the great pyramids. Much easier to figure out a location if you have such obvious landmarks.
Yeah, since then I've got a picture of Nixon in front of the white house: only 12m off.
Hah, I had a super easy one in front of the National Gallery in London - 6.3 m off :)
Amazingly, though I got the year correct as well (1973) - total guess!