On the north-east side of the Hornsey Road/Seven Sisters junction there are big wooden doors where there you'd expect a building. Peer through a hole cut into the doors and you see this:
This sign suggests that something might be about to happen:
It'll be a building of some sort. It might even be a good, useful, liked building.
I kind of wish someone would loop ropes over those big steel girders and set swings up.
Or (and this is almost on the fringes of possibility) that someone like Transition Finsbury Park would take it over for a while as happened with the Blackstock Greenhouse.