Leavenworth is best known for the "Federal Pen" or "Big House", which is now a medium-security prison. Construction of this historic prison began in 1897, with the first cell house opening in 1906. The Federal Penitentiary has been the home of Kansas City Boss Tom Pendergast, George "Machine Gun" Kelly, "Bugs" Moran, Manuel Noreiga, and Leonard Peltier. Their most famous prisoner was Robert Stroud, known in the movies as the "Bird Man of Alcatraz". In real life he did all of his bird work in Leavenworth, serving 28 years here before being transferred to Alcatraz.
A small herd of buffalo is located west of the main building and can be viewed from a pull-off area on Metropolitan Avenue on the north side of Leavenworth. NOTE: No public tours are available but can be photographed from across Metropolitan Avenue.