Lombard Street in San Francisco
Funny....I remember Lombard Street being a lot more twisty and slanted, but then again, it's been 15 years since I've been to the Bay Area.

Bill Cosby had a hilarious bit on this unmistakable piece of SF roadway. If I'm not mistaken, it's one-way (downwards), and is adorned with some of the best-looking flowers you'll ever find. (Also, the surrounding property was once listed as being the most expensive in the United States and its territories, followed closely by Honolulu, and, ironically, Guam.)