San Francisco is one of the few places in the world where you can ride on a national historic landmark. The cable cars are the world's last manually operated cable car system, a tramway whose cars are pulled along by cables embedded in the street. Refurbished and equipped with new tracks, cables, turnarounds and cable propulsion machinery, they operate much as they did in 1873 when Andrew S. Hallidie guided the first car down the Clay Street grade. Once upon a time, cable car lines serviced the entire city. Today, only three lines remain, but they can take you to some of San Francisco's most popular neighbourhoods.