Although they may not be San Francisco's most practical means of transportation, cable cars are certainly the best loved and are a must-experience when visiting the city. Designated official moving historic landmarks by the National Park Service in 1964, they clank up and down the city's steep hills like mobile museum pieces, tirelessly hauling thousands of tourists each day to Fisherman's Wharf at the brisk pace of 9 miles per hour.

As the story goes, London-born engineer Andrew Hallidie was inspired to invent the cable cars after witnessing a heavily laden carriage pulled by a team of overworked horses, slip and roll backwards down a steep San Francisco slope, dragging the horses behind it. Hallidie resolved to build a mechanical contraption to replace horses, and in 1873, the first cable car made its maiden voyage from the top of Clay Street. Promptly ridiculed as "Hallidie's Folly," the cars were slow to gain acceptance. One early onlooker voiced the general opinion by exclaiming, "I don't believe it -- the damned thing works!"

Even today, many visitors have difficulty believing that these vehicles, which have no engines, actually work. The cars, each weighing about 6 tons, run along a steel cable, enclosed under the street on a center rail. You can't see the cable unless you peer straight down into the crack, but you'll hear its characteristic clickity-clacking sound whenever you're nearby. The cars move when the gripper (they don't call themselves drivers) pulls back a lever that closes a pincerlike "grip" on the cable. The speed of the car, therefore, is determined by the speed of the cable, which is a constant 9 1/2 mph -- never more, never less.

The two types of cable cars in use hold a maximum of 90 and 100 passengers, and limits are rigidly enforced. The best view (and the most fun) is from a perch on the outer running boards -- but hold on tightly, especially around corners.

Hallidie's cable cars were imitated and used throughout the world, but all have been replaced by more efficient means of transportation. San Francisco planned to do so, too, but met with so much opposition that the cable cars' perpetuation was actually written into the city charter in 1955. The mandate cannot be revoked without the approval of a majority of the city's voters -- a distant and doubtful prospect.

San Francisco's three existing cable car lines form the world's only surviving system, which you can experience for yourself should you choose to wait in the often long lines (up to a 2-hr. wait in summer).

The Secret to Catching Cable Cars -- Here's the secret to catching a ride on a cable car: Don't wait in line with all the tourists at the turnaround stops at the beginning and end of the lines. Walk a few blocks up the line (follow the tracks) and do as the locals do: Hop on when the car stops, hang on to a pole, and have your $5 ready to hand to the brakeman (hoping, of course, that he'll never ask). On a really busy weekend, however, the cable cars often don't stop to pick up passengers en route because they're full, so you might have to stand in line at the turnarounds.