Begin with a fortifying bayside nosh at the Ferry Building, then head up one of the city's great thoroughfares, Sacramento Street, through the canyons of the Financial District and up vertiginous Nob Hill. Take a breather at Huntington Park, savoring the rarefied oxygen, and then descend to Polk Gulch for a revivifying bivalve or two at Swan's. Cross 101 and make your way past Lafayette Park and the splendid mansions of Pacific Heights, knock back a quick one at the Elite on Fillmore, and chase it with something from one of the swell snackeries of Presidio Heights. Cut down Arguello, lingering perhaps at one of Clement Street's fragrant bakeries, and enter Golden Gate Park. Meander through the greenery as you choose, checking out the Portals of the Past and the buffalo paddock, following the setting sun if you get lost. Before long, the windmills will loom ahead, and beyond them the limitless Pacific and no farther to go. Luckily, the Beach Chalet appears to be open for business.