Lombard Street is an east-west street in San Francisco, California. It is famous for having a steep, one-block section between Hyde and Leavenworth in which the road has eight sharp turns that have given the street the name "the crookedest street in the United States." The Powell-Hyde cable car line stops at the top of the block.
The design was created in 1922 due to the hill's natural 27% grade, which was too steep for most vehicles to travel. This section of street can only be traveled one-way, downhill, and it is all brick.
If you're into twisty streets, you should also check out Vermont Street.
West of the famous hilly section, Lombard Street is actually part of the path followed by US 101, and will help take you to and from the Golden Gate Bridge.