The bridges at Biltmore were designed by Frederick Law Olmstead as part of the overall design of the estate and are incredibly well executed. The brick ones, although they vary considerably in size, are all detailed the same and are built of brick made on premises and from clay harvested from the French Broad River. The stone bridges tend to be less refined and are located, in general, farther from the house on roads that were part of the estate circulation plan. They are appropriately rural in nature and are built primarily of native granite. In the Azalea Garen, there are small wood bridges and very simple stone ones that are all scaled to pedestrian use. The attention to approriate detail is wonderful throughout.