It would help if I knew what most of the things on the map ARE.
That's a valid question. Their obstructions. Science gear, test tubes, etc. There is a library somewhere on the right, and a large spooky tome thing over there too all necronomicon like.
In your case you're in the rafters, which is why I left the light brown criss crossing thing, for you to clamber across. Rats are up there, but I'm not placing all of them. It's basically a ceiling-wide thin swarm.