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
Double-deckers are primarily for commuter transport but open-top models are used as sight-seeing buses for tourists. William Gladstone, speaking of London's double-deck horse drawn omnibuses, once observed that "...the best way to see London is from the top of a bus".