Ornate doors are found inside Quicksand Caves. They block a variety of Notorious Monsters and passages throughout the caves.
To open an Ornate door requires three or more weight points to stand on the switch for a pressure door to open. Tarutaru are one weight point, Hume/Elvaan/Mithra are two weight points, and Galka are three weight points. Put another way, a weight switch requires at least three Tarutaru, one Hume/Elvaan/Mithra and one of any other race, or one Galka).
Examples of weight switch combinations needed to open an Ornate Door:
As long as thee or more weight points are standing on the pressure switch, the Ornate Door will open.