Double-decker bus
The first commercial horse-drawn double-decker omnibuses were introduced in England in 1847 by Adams & Co. of Fairfield, Bow, then improved upon by John Greenwood, who introduced a new double-decker in 1852.
Double-decker bus
In San Francisco, California, the San Francisco Municipal Transportation Agency operated one Alexander Dennis double-decker bus as a demonstrator between 12 December 2007 and 8 January 2008. The bus was running on some high capacity routes as trial.