The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
The Beaverkill is perhaps the most famous fly fishing stream in America, largely because of its history, and it can still be a good one if you don't let its history spoil your expectations.
Almost every pool has a name and a story or three in the great works of fly fishing literature.