Where are some secret locations?

Hint 1 of 4:

(1) In the first dark room, look in the compartments at various spots in the
room.

Hint 2 of 4:

There's a hidden passage behind one of them.

Hint 3 of 4:

One of them leads to place that has 1138 on the monitor, a reference to one
of George Lucas' projects.

Hint 4 of 4:

(2) In the second dark room (behind the lift, past the force field) there's a
hidden door in the northeast corner.