1. the nest of a bird, such as an eagle, built on a cliff or other high place 2. a house or stronghold perched on a height
I saw this word in The Hobbit, which I'm currently reading to my son. It was spelled eyrie, though, which must be a British variant or something.
We have an eagle aerie within about two blocks of our house in Tampa - high atop a cell phone tower! This is definitely an urban setting, but with quite a few little lakes nearby, evidently providing the magnificent birds with good fishing. In fact, central Florida has many such nests available for viewing by observant people such as my wife.