I can't find a way to drow city!!! where is it?

It's in the NE corner of the map. You won't want to just walk in though. Have you seen the Deep Gnomes yet? I will say no more unless you ask me to do so.

Yes there is a little path in the middle eastern area that leads to it.

I've never thought it was behind githyanki

Umm...You mean Sahuagins? IIRC, there's no githyanki in the underdark except who're captured.

Well, if you mean sahuagins, then drow city is north of them.

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if you go north, you will see the bridge with some conflicts. After crossing the bridge go north east alone the small path, then there'll be the drow city.

And I do, too, not recommand go straight to the drow city.

There would be if he has already been to the illethid lair.
And go ahead. Try getting into the drow city. You cant unless you have met Adalon.

Shaguin!?! Where did Shaguin get into the Underdark? Which mod are you playing man ;)