D20 greetings to all DnD fans

Link to the maps
http://www.resonant.org/games/eye_of_the_beholder/eyeofthebeholder.html

I am about to slay the beholder, but I can't get to the portal which leads to Level 12.
Because the door requires a Drow key.

I have attached two maps, one original and the other is edited, of where I need to get to.

(Number 1) on the second map is the location of the portal.

And the highlighted region of the second map is the location of the key (number 2), but I have no clue how to get there.

Thank you very much
gogwitcher300

Thank you very much
dr.schliemann

Yes, I found the tiny button in the pillar, a wall opened, and I found a mind flayer with the key.

Once again thank you very much
gogwitcher300

My pleasure: thanks to you for your good taste in videogames.