Walk down Castro St between Market St and 19th St and you're likely to bump into bare-chested men in leather chaps, gray-haired bifocaled women holding hands, gay dads comparing Snuglis, and tourists speaking in French, Italian, and the soft consonants of the deep South. The Castro is a neighborhood, an icon, and a tourist attraction. And that's precisely how its residents - from the man who strolls the street dressed in pink angel wings, to the straight couple taking their 4-year-old to see "Yellow Submarine" at the Castro movie theatre - like it.  Up until the 1960's, The Castro was called Eureka Valley and was mostly a neighborhood of working-class Irish immigrants. By the mid-seventies, it had become the "Gay Mecca," and was responsible for electing San Francisco's first openly gay politician - Harvey Milk. Milk, who was known as The Mayor of Castro St, ran his campaign from his camera store at 575 Castro (now Skin Zone, a shop which stocks pretty much everything that bubbles, moisturizes, and exfoliates). Today, there's a painting of Milk, who was assassinated by Dan White in 1978, on the building above his old camera shop where he can keep an eye on the neighborhood.  During the eighties, at the height of the AIDS epidemic, The Castro became a neighborhood of ghosts. Fragile men in their thirties moved slowly across Castro Street, leaning on canes or their friends' shoulders. Gay men and lesbian women cooked meals and dropped them off at the homes of ex-body builders who were too weak to go out. People who were not yet forty spent much of their time going to the funerals of their contemporaries.

Today, The Castro is once again thriving. Settled gay couples, survivors of the epidemic, prune roses in front of their Victorians, straight parents walk their kids over to the Harvey Milk Academy, and young lesbians dressed in baggy shorts dash into Nirvana (544 Castro) to slurp Asian noodles. The best way to see The Castro is to walk it; stopping into A Different Light Bookstore (489 Castro St) which stocks "queer books for smart people," ordering cappucino in Pasqua (4094 18th St) where the Bears - burly gay men who favor flannel shirts and facial hair - gather to sip lattes; buying a needlepoint pillow that says "Queen" or a Wizard of Oz mousepad at Under One Roof (549 Castro), which donates its profits to various AIDS agencies; and visiting Does Your Father Know (548 Castro) to browse among the unclad Davids and shelves of well-endowed Billy dolls. In fact, there are so many prominently presented examples of male genitalia on Castro St, it's not uncommon to wonder if The Sausage Factory restaurant is about something other than Italian food. (It isn't.) Every October, Castro St closes to traffic and holds a street fair where the people-watching rivals whatever is being displayed in the booths.  Tuesday through Saturday, Trevor Hailey, a Castro local and retired nurse, leads a walking tour called Cruisin' the Castro. The tour runs from 10 am to 2 pm and costs $40, which includes lunch. Reservations are required and can be made by calling 415-550-8110. For more information, visit Trevor's websit at www.webcastro.com/castrotour.