The Flight Cage or the Bird Cage was a 228-foot long, 84-foot wide and 50 foot high flight aviary built by the Smithsonian Institution to house the U.S. bird exhibit. Construction cost was $17,500. It was split lengthwise into two sections by a wire mesh wall. Visitors walked through a tunnel of wire mesh to view the birds.
The city of St. Louis purchased the Bird Cage for $3,500 and that acquisition led to the establishment of the St. Louis Zoo.