Update — March 2018: The building installed two-stair handrails on top of the platform.
Long two stair Philly step / manual pad.
Bust — ♦♦♦♦♦: Weekend spot. If you skate it when the building is open, you will be told to leave.
Location: Kent Avenue in between S 6th Street and Broadway in Williamsburg. Take the J or Z train to Marcy Avenue, and skate west on Broadway until it hits Kent. Make a right on Kent, and it is in the middle of the block.
Pictures (Click to Enlarge):