Railroad Heritage Corporation
http://www.railroadcity.com/curve.htm
This site of the Railroaders Heritage Corporation features Pennsylvania Railroad Horseshoe Curve, the Railroaders Memorial Museum, and related railroad attractions in Altoona. The link to Horseshoe Curve history provides a useful, brief timeline of Horseshoe Curve events from the tourism view point.
Referenced in:
Altoona
Altoona Horseshoe Curve: A Vital Link