177-year-old B&O "John Hancock" on exhibit at the B&O Railroad Museum. The locomotive was built in 1836 and survived in service long enough to be preserved by Col. Pangborn for the B&O's exhibit at the 1893 Colombian Exposition. It was made operational for 1927's "Fair of the Iron Horse," and today is housed indoors in Baltimore, one of the oldest original American locomotives in existence. For decades it was incorrectly displayed as B&O No. 3, the "Thomas Jefferson."