Don't blink or you might miss this alley off of Union Square, between Post and Geary. Once the city's scandalous red-light district, it now sports San Francisco's largest concentration of luxury retail shops, including Hermes, Gump's, Chanel and a host of other high-end stores. Be sure to visit Britex: four floors of every kind of fabric imaginable and thousands of styles of buttons. Maiden Lane also has a handful of outdoor cafes and its own opera singer, tenor Robert Close, who has been entertaining visitors for 25 years. http://www.visitunionsquaresf.com/about_union_square/maiden_lane/. View Maiden Lane in Google street view.