This was one of the first concepts I made getting Mines of Moria off the ground.
I don't have as much experience doing environments as I do characters so I learned a lot from doing these early projections of key areas. I actually intended this doorway and the bridge inside this natural cave to be a unique POI, like a special place devoted to all the past Dwarven kings with all their portraits carved into stone. Dwarves had a huge respect for the natural formation of stonework, so art like buddhist relief sculptures were a big influence on this idea.
They liked the motif so much they just spammed it everywhere so all the doors in Moria have a dwarf head above it. It's kinda creepy, but I guess that's the point.