Complex sentence: The Land of Green Ginger contains what may be the world's smallest window, being a slit which was used by the gatekeeper of the George Hotel to look out for stagecoaches and customers.
Split into simpler sentences: The Land of Green Ginger is also where what may be the world's smallest window can be seen. It was used by the gatekeeper of the George Hotel to look out for stagecoaches and customers.