Dwarven gates
The natural proclivities of the race and thousands of years of warfare have made the dwarves master defensive architects. The typical dwarven gate is a large circular entranceway, which can be sealed by a huge, thick disk of carefully worked stone. The stone disk rests on its edge and is so perfectly weighted and tooled that it can be rolled side to side by a dwarven child. The disk door is set into a space within a wall adjacent to the gate opening, and rolled sideways along a track to close the entrance. As these doors are rolled open or closed, the crescent opening they form artistically complement the Mother Moon and Father Sun motifs that typically adorn the gates and door stones.