On the way east to visit Glen's mom we stopped at the
Allegheny Portage R.R. national historic site and at
Horseshoe Curve west of Altoona, PA. Hiked trails at APRRNHS to view a
skew arch bridge built to carry a roadway (turnpike) over the train. Stones were laid without mortar and the angle of the bridge to the arch was skewed, not 90 degree angles. Very large, sturdy stone building at the summit (your tax dollars at work thanks to
former Rep. John Murtha) to house historical exhibits about the portage railroad which was in use from about 1834-1854, until the PRR built the track over the Allegheny Mtns at Horseshoe Curve.