This winding mountain road was constructed in 1933. It is famous for its scenic, one-lane tunnels. Legend says that engineers once said it couldn't be built. Every trip along this road will be a different experience. With the beauty of the mountains and valleys as its backdrop, this unusual and captivating road was specifically designed with a tremendous amount of curves in order to limit the speed of travelers to 35 miles per hour so that they could enjoy the beauty of the Black Hills.