Pick one category for the following text. The options are - company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work. Horseshoe Curve (Pennsylvania) - Horseshoe Curve is a three-track railroad curve on the Norfolk Southern Railway's Pittsburgh Line in Blair County Pennsylvania. The curve itself is about 2375-foot (724 m) long and 1300 feet (400 m) in diameter; it was completed in 1854 by the Pennsylvania Railroad as a way to lessen the grade to the summit of the Allegheny Mountains.
Building