My office and the math main office is on the 4th floor of McHenry.
Finding the fourth floor is not entirely trivial. There are three recommended routes.

(1): (most obvious) Take the elevator from the alcove off the front lobby.

(2): Take the elevator at the back of the building in the skinny concrete hallway.

(3): Take the stairs, just near those back elevator of (2)

and one not recommended route

(*) take the main library stairs to the 4th floor, set off the fire alarm, come on in.

I've been told that the stairs are the old chancellor's secret escape route
They look like a route for servicing machinery. Students, pointed to them by staff, often
say ``This can't be right! It doesn't look like students aren't allowed here.'' Finding
these stairs or back elevator involves navigating a short segment rabbit's warren
hallways if you enter on `floor 2' or a long torturous rabbit warren of hallways if
you enter via the outside 1st floor entry at the building's front.