Photosynth:
http://photosynth.net/view.aspx?cid=b1a118be-58ef-4a51-96f0-6a1c838587e9
Look up... and see how arches form...
And... for fun... here's one from The Diving Board taken with a camera instead of iPhone:
http://photosynth.net/view.aspx?cid=dfad42b2-5276-4016-986a-a79d564d99b5
There's more to be found there for those so inclinced