Selby Abbey, Yorkshire, England (f. 1069) is one of the few surviving mediaeval abbeys. It contains a Rare and Famous Find! yes, yes it does. A 14th century Washington Window in one of the south chapels. This window shows the coat of arms of the Washington Family; of whom George Washington (1st President of USA) was descended. Washington used his family coat of arms as inspiration for the Stars and Stripes.
I like this story because it demonstrates the intertwined history of the States and Great Britain, a subject I am certain is dear to your heart. (image by woodytyke on flickr)