How to lose something larger than the Empire State Building. Shipton's Arch

It is easy to lose things. I have lost count of the number of decent pairs of sunglasses I have lost in my travels around the world. Yet to lose an arch, and not just any arch, but the largest arch in the world, which could easily fit the Empire State Building in New York into it with room to spare, well that seems to be a whole new level of carelessness.