I've seen these often in older buildings. It's probably a type of fire door- lead sheets nailed/adhered to a the door, most likely heavy wood- (don't know, never looked behind any sheet) but it is heavy, hence the pulley system which I've always seen with this type of door. I've seen them on floors at the entrance to a fire-escape stairwell, in common areas at the head of a long hall, and used with old-style elevators.
Alot of older buildings were either joined together from two separate bldgs to become one, or one bldgs separated to become two. I'd imagine a fire door would be required between two bldgs where they had a common opening, which looks to be the case here. I'm guessing when it was renovated for condos/apts, the door had a cool factor, so the entrance was brickedup but the door kept.
I met Danny (via his mom) briefly way back when before he started his life-after-partridges, and his suck-the-air-out-of-the-room personality even then was pretty much like it is now. I think it's great he lives here, and wish him luck wherever he's going next.
SooooooooooooooooPER ........................ SL O WD O WN