New York City's newest lit landmark is the Park Avenue Viaduct. The lighting is a group effort between the Grand Central Partnership, NYC DOT, and Metro-North Railroad - the new colored LED lights went "live" December 16th, just in time for Christmas colors.
Vehicular viaducts around Grand Central were part of Reed & Stem's concepts for the Terminal, and part of the reason why they were selected for the station's commission. Although Warren & Wetmore attempted to nix the viaduct, it was eventually completed in 1919, 6 years after Grand Central opened.
