40 feet wide and 200 feet long, the completed structure was fine for equestrian traffic, but woefully inadequate following the arrival of the automobile, and thereafter a notorious traffic bottleneck. Razed in 1950 as part of the neighborhood upgrade around the UN, it was replaced in 1952 with the streamlined bridge that still stands today.
Above, the tunnel in the 1940s. View from First Avenue looking west down 42nd Street.
In addition to vehicular traffic, the tunnel was used by the 42nd Street streetcar line.
Staircases around the arch provided access to First Avenue from Prospect Place.
The tunnel pictured on the cover of Pencil Points, an architectural journal, in 1934.