The rear western elevation is less elaborate than the front facade, with some windows not having any decoration at all. Two matching polygonal towers in the center are connected to the polygonal south turret by an open loggia that opens the main rooms of the house to the views of the Blue Ridge Mountains in the distance. The loggia is decorated overhead with terracotta tiles set in a herringbone pattern. The self-supporting ceramic tile vault and arch system was used extensively inside and outside of Biltmore, and was patented by Rafael Guastavino, a Spanish architect and engineer who personally supervised the installation. The limestone columns were carved to reflect the sunlight in aesthetically pleasing and varied ways per Vanderbilt's wish. The rusticated base is a contrast to the smooth limestone used on the remainder of the house.