January 21st. Big City Surreal

I wandered across this today. This was the view in through the doors, in the middle of a a thick, 10-foot high, 100-foot long concrete wall.

I was wondering, whose extremely expensive, exquisitely maintained backyard is this? It's two blocks from a homeless encampment (although I've found that neighborhoods and streets here can change character within even a 1/2 block. Just 20 feet and it all feels and looks different.) Handily, there's a helpful plaque next to the door.