This is a tower, inspired by the Tooth Fairy’s Tower from Hogfather. I’m trying to figure out why certain of my arches turn bright red, especially depending on the view angle. Looking up, almost all of them are red. In the close up, one arch is red and one is not. If I duplicate the non red arch and move it, it turns red as well. The lighting comes from each of the torches and three lights in the middle of the tower.