The Nanning Butterfly Tied Arch is a unique three-dimensional (3D) arch that incorporates several design and analysis innovations. The curved orthotropic deck with a horizontally draped internal tie resists both arch thrust and serves as a horizontal arch to resist out-of-balance lateral forces imparted by the asymmetric arch ribs. This force resisting system was confirmed and refined by 3D shape-finding studies. The arch rib segments are orthotropic boxes, which is a first for long span arches. And most notably, this is the last bridge worked on by the late Prof. T.Y. Lin.