Stretching from The Presidio east to The Embarcadero (with a gap on Telegraph Hill), most of the street's western segment is a major thoroughfare designated as part of U.S. Route 101. The famous one-block section, claimed to be "the crookedest street in the world", is located along the eastern segment in the Russian Hill neighborhood. It is a major tourist attraction, receiving around two million visitors per year and up to 17,000 per day on busy summer weekends, as of 2015.
The street was named after Lombard Street in Philadelphia by San Francisco surveyor Jasper O'Farrell.
Lombard Street's west end is at Presidio Boulevard inside The Presidio; it then heads east through the Cow Hollow neighborhood. For 12 blocks, between Broderick Street and Van Ness Avenue, it is an arterial road that is co-signed as U.S. Route 101. Lombard Street continues through the Russian Hill neighborhood and to the Telegraph Hill neighborhood. At Telegraph Hill it turns south, becoming Telegraph Hill Boulevard to Pioneer Park and Coit Tower. Lombard Street starts again at Winthrop Street and ends at The Embarcadero as a collector road.
Lombard Street is known for the one-way block on Russian Hill between Hyde and Leavenworth Streets, where eight sharp turns are said to make it the most crooked street in the world. The design, first suggested by property owner Carl Henry and built in 1922, was intended to reduce the hill's natural 27 percent grade, which was too steep for most vehicles. The crooked block is perhaps 600 feet (180 m) long (412.5 feet (125.7 m) straightline), is one-way (downhill) and is paved with red bricks. The sign at the top recommends 5 mph (8 km/h). The segment normally sees around 250 vehicles per hour, with average daily traffic reaching 2630 vehicles in 2013. During peak times, vehicles have to wait up to 20 minutes to enter the Crooked Street segment, in a queue that can reach Van Ness Avenue.
According to wikipedia