What is the purpose of these metal doors in the Circle of Magi tower?

In the Circle of Magi tower, in the Senior Mage Quarters there are metal doors that cannot be picked, or opened otherwise:

What is beyond them, and how does one get inside?

Solution 1:

What's behind them is a dungeon meant for the mage origin story. Spiders infested it and one way to get a rod of fire was to help the senior enchanter kill them. Since all of the possible wardens existed whether or not you played them, there's honestly tunnels beyond them with a couple empty creates so even if you could get in during the main story-line it wouldn't be worth it.

Solution 2:

If I remember correctly, that door is a part of the mage origin story.

You have to go in there to clear out some spiders.

I don't think it's accessible during the main story.