The most noteworthy feature is the royal castle atop a large chalk cliff, which began as the site of William the Conqueror's late eleventh-century fortress. Windsor Castle has been expanded and rebuilt over the centuries, and has long been a royal residence.
Windsor had many personal associations for the Shelleys. Percy Shelley lived there when he met Mary, and the two returned there in 1817 to set up their household in Marlow, where most of Frankenstein was written. Mary later set parts of The Last Man in Windsor.