Enter the front gate of Gallaudet University on Florida Ave NE. You will see a security in a tiny security house. Make a left on Lincoln Circle NE. Continue curve right on Lincoln Circle NE. Make a left at the stop sign on the stop sign. Continue straight all the way until you will see a garage. Go in the garage and drive all the way up to the top roof.
You'll find the key located in the sun visor organizer on the driver side, please return it there at the end of your trip.