SIN125_200805_21
Existing comment: Smithsonian's National Zoo -- 125 Years

The O-Line:
In 1995, the Zoo debuted the O-Line, a series of towers and vine-like cables. It allows our orangutans to travel between the Great Ape House and Think Tank, if they choose to do so. Still innovative today, the O-Line is the only "orangutan transport system" of its kind.
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