Horseshoe Curve, Altoona, Pennsylvania

Altoona, Pennsylvania, October 12, 1934

 

(Click the image for a larger version.)
This photograph is from the panoramic photograph collection of the American Memory project at the Library of Congress. The horseshoe curve carried the Pennsylvania Railroad at a reasonable grade through the Allegheny Mountains. Designed by John Edgar Thomson (who soon become president of the PRR) and Herman Haupt (who later started digging the Hoosac Tunnel in western Massachusetts and was a Union general in the Civil War) designed the  curve. The horseshoe curve opened on Feburary 15, 1854.

Here's the satellite image from above (via Google Maps). Click the image to view the map itself.