Beyond the tinted windows of the double-decker red tour buses that bumble through the city, the streets of San Francisco offer invisible cultural phenomena and flavors of each neighborhood that can only really be tasted by hitting the pavement. Neighborhood Public Radio's Alternate Soundtrack City Tours takes a conceptual approach to understanding the city, broadcasting neighborhood tours every weekend over a guerrilla-style FM transmitter. Past tours have included a jaunt through what used to be Woodward's Garden, an eccentric Gold Rush-era millionaire's personal grounds-turned amusement park, as well as a Hamburg artist's recounting of stories from her favorite Mission locales when she lived here five years ago. The first Saturday of the month, these tours are led by the local artist who created that month's soundtrack. If you miss the artist-led tour, simply obtain a map from NPR's partner, Southern Exposure gallery, and tune in a portable FM radio to 89.9. The audio runs on a loop all weekend long.