I can definitely recommend Ultima Underworld 1+2. Those were my very first dungeon crawlers back in the 90s.

Legend of Grimrock is another one I can recommend if you are looking for a new game that pays homage to games like Eye of the Beholder or dungeon Master.

Arx Fatalis is also awesome, is set in a world completely underground and still looks good even to this day. Has a unique gesture-driven magic system where you draw the runes for the spells.

I would be remiss if I didn't give an honorable mention to Stonekeep which is an Interplay classic, also from the golden age of the 90s.

Hope that helps :D

I, too, vote for Ultima Underworld. It's sexy.

Fixed that for you :P