How to get to the other side of the door?

[RavenHawk]

Ok I am on level 3 and have just got to the part where I have to raise the gate to let the car get to the west side of the map. In the room where grama has kill the soilder and after you kill all the idiot there are two door in form of me. One has the red circle with a slash through it and the other says "Open from the other side" How do I get to the other side of said door? Where is the passage to it. I cannot use a no cxlip cheats to see and I am stumped. Any help?

[RainbowGiraffe]

Once in Berlin you will see some dirigibles.
You know what they are called in German? Zeppelin.
What do you spray all over the Nazis? Lead.
This reminds me of this one band. Led Zeppelin. And this song. You know which one?
Stairway to Heaven.

Use the stairs.

[RavenHawk]

Ok I went up the said satirs to my left whre the elevator is. I found no access point to get to said door down below! Is there a vent or grate I have blow up to gain accee? I know this sound silly but I have completed the game and found all secrets nbut this one door has me scratching my head