Trapped!

You awaken, your eyes filled with sleep. You view your surroundings and gasp. You are in a large room with steel walls. Panicking, you search for a door, but you are crestfallen to see that there is none. You look up, bright light flooding into your eyes. A glass roof is above you, at least 3 stories over your head. You can not see the sun, but you know that when you could, it would get MUCH hotter in there. You scream in terror and look for a trapdoor, but you can't find anything. That is when you notice a small rope hanging from the wall about four feet above you.