Trey K.
Yelp
BLDG92 is a terrific little museum dedicated to showcasing the Brooklyn Navy Yards historic past, as well as its present mission as a campus for sustainable manufacturing.
The museum is free, and it's a little small, but definitely a nice place to spend an hour. Plus, since it's free, it's a nice place to take a walk and wander around.
The higher up you go, the better views of the industrial water front, and while I'm not crazy about the food at the café on the top floor, the views can't be beat.
My favorite exhibit is a map of the Yard protected on a table. It is animated to show how the Yard developed and changed over time, and it's amazingly i interactive: for example, I noticed a burning ship drifting through the scene. I touched it, which opened up a window about the 1960 fire on the USS Constellation, which claimed 50 lives.
A great place to learn about Brooklyn history, especially if you combine it with one of Turnstile Tours' tours of the Navy Yard.