Some of Robert C. Pritikin's neighbors are going to be surprised when they read this. You see, the exterior of his apartment building--that's right, apartment building--isn't all that spectacular. It stands next to a laundry on a shady street in San Francisco's Pacific Heights and it blends neatly--even inconspicuously--into its milieu. But there's surprise awaiting you if you should ever visit Mr. Pritikin, a successful advertising executive, in the second of the six apartments. A carpeted hallway takes you to a balustrade overlooking a two-story living room. You descend via a graceful circular staircase--designed, like the rest of the apartment, by architect Robert Crutchfield--and find yourself facing seven gargantuan glass doors. They open at your touch and the living room expands to embrace an L-shaped swimming pool and a luxurious garden boasting full-sized trees and giant hanging plants. Above is a balcony that supports a dining area and a "library"; the latter is enriched by mahogany paneling and a brown-velvet wall sporting three stained-glass windows, hundreds of years old. The decor of the apartment, reflecting Pritikin's myriad interests, is eclectic to the nth degree. On display are spears that he brought back from Australia; antique coffee grinders from Guatemala: pieces of magic apparatus used by Carter the Great, a popular wizard of the Twenties; and literally thousands of mementos and art objects. They range from kinetic sculptures, which Pritikin doesn't necessarily recommend ("If the artist goes out of town and the sculpture goes on the blink, you've got a heavy problem") to a "small, worthless rock" that, according to Pritikin, "represents my thoughtless contribution to the deterioration of the Colosseum in Rome." And that's a sobering reference, in the context of the Bay Area: for if San Francisco is ever leveled by the natural catastrophe that all the scientists are predicting. Pritikin's pad, like the Colosseum, may be reduced to fragments. For the foreseeable future, however, the man has a good thing going. As a recent guest of his remarked--in an understatement for sure--"Anybody in the city could do worse."