On a sunny September day, Woody Miller strolls through the district, known as Castro. He's tall and fit, with a long grey beard and heavy silver nose ring -- and wearing nothing more than sneakers, a baseball cap and a watch.

"I go naked on a nice day because I like the feel of the sun and the air on my skin," says Miller, 55, who is one of the city's growing number of public nudists, popularly known as Naked Guys.