Lombard Street

The one-block crooked section was built in 1922 by engineers who needed a way to make Russian Hill's steep 27 percent grade passable for cars, and their solution, eight sharp switchback turns paved in red brick, has been popularly known ever since as the crookedest street in the world, even though nearby Vermont Street in Potrero Hill is technically steeper in grade terms.

Traffic runs one way downhill through the switchbacks, past manicured hydrangea beds that bloom for much of the year, while pedestrians can walk down the block's own staircases along the sides for a closer view. Because the block draws such heavy visitor traffic, cars can face long waits at busy times, so many visitors choose to walk down instead and photograph the curves from the sidewalk at the top or bottom of the hill.