A view of DN&P "hill hell" known as the Loop with its wooden trestle over Tunnel 33, the Rifle Sight Notch Tunnel, with a train on the trestle and another approaching the tunnel. Lettered "1634 WORLD RENOWNED LOOP DENVER NORTHWESTERN & PACIFIC Ry. MOFFAT ROAD". Attributed to McClure and retouched by him - 1904-1913 - Denver Public Library MCC-1634.