Judging by the amount of junk stored in there on the virtual tour it doesn't look like its being used as a fire escape, if there is no right of access from the rest of the building and they have other ways of getting in and out then it could possibly be made into an odd 3 storey property with maybe a narrow spiral staircase, alternatively it would make a good greenhouse. If it is the fire escape then it needs clearing and is useless for anything else.