There is not one... but two great beer festivals taking place in Brooklyn today.
First up, Red Star (37 Greenpoint Avenue) hosts the 2nd annual Greenpoint Beer Festival which will feature 33 craft and microbrews. There will also be live musical performances throughout the day and the festivities kick off at 2PM. It's free to get in, but six beer samples will cost you $20 bucks.
Down in Cobble Hill, The Brazen Head hosts its 22nd Real Ale Cask Festival. There will be more than 20 rare and delicious cask beers being poured until 2AM today and tomorrow. It's free to get in and there is no minimum purchase required.