The best known and oldest one operating is the Wuppertaler Schwebebahn in the German city of Wuppertal. Unlike most Monorails the Trains do not ride 'on' a single rail but instead 'hang' from a single rail. In Operation since 1901 as a public transportation system.
Other famous monorails are of course those in Disneyworld and in Tokyo.
Las Vegas has a relatively new Monorail as well.
Tokyo Monorail was created in 1964.
Carowinds Monorail ended in 1994.
Carowinds Monorail was created in 1973.
Sentosa Monorail ended in 2005.
KL Monorail was created in 2003.
Johnny on the Monorail was created in 1980.
Metro Monorail was created in 1988.
Moscow Monorail was created in 2004.
Kitakyūshū Monorail was created in 1985.
Okinawa Monorail was created in 2003.
Sentosa Monorail was created in 1982.
I can take the monorail to work next week!