Nob Hill is where the railroad barons built their mansions to look down on the city they owned — and where the 1906 fire burned every one of them to the ground. What stands now grew up out of the ash: the grand hotels, the cathedral, and the cable cars that made the hill liveable in the first place.
Start where the California Street and Powell lines cross on the summit, two cable systems hauling through one intersection. The Fairmont and the Mark Hopkins face each other across the street, both built over the barons' burned-out plots; the Fairmont lobby is worth a look for the gilt alone. Cut to Huntington Park, a formal square on Collis Huntington's old block, and across from it Grace Cathedral, its doors cast from Ghiberti's Florence panels. Walk the labyrinth set into the floor; it's there to be walked.
Then down the north slope to the Cable Car Museum, the working powerhouse where the great wheels pull every cable in the city — free, and the answer to everything you've watched climb. End on Hyde Street, the bay and Alcatraz opening ahead, the Powell-Hyde car ready to drop you down.