Although commonly thought of as a modern invention monorails have been with us since 1825 and self-propelled since 1876. The oldest surviving monorail was built in 1901 and is still in operation. By 1914 monorails had developed into a form that is similar to today's straddle-beam systems.
1914 Genoa Monorail (The Monorail Society, 2008)
Many monorails were built to showcase technology for a world's fair or expositions, such as the ones in Philadelphia (1876), Genoa Italy (1914), Turin Italy (1961), Seattle (1962), and New York (1964).
Of course the best known monorails are those at Disneyland and Walt Disney World, not surprising since the latter is the #1 tourist destination in the world. These monorails have been in daily operation since 1959 and 1971 respectively, transporting millions of guests. Most monorails built since that time are based on similar technology pioneered by Alweg and continued by Hitachi and Bombardier.
Disney's models are readily available and reasonably priced, and form the basis of most monorail modeling. Schuco made Disneyland models for years and these are collectibles. The only other well known model is by Rokenbok but their model does not represent any prototype and is of little interest to most modelers.
The Monorail Society. (2008). Retrieved March 13, 2008, from The Monorail Society Web site: http://monorails.org