"I mean, it's a marvel," Dr. Weiss said, swinging open a window above a view of the East River, which is more familiar to me from an airplane when you land at La Guardia. Yes, the windows open. "You couldn't do it today," he added. "Forget it."

Dr. Weiss is, appropriately, a product of the American dream working inside of an American icon.

"My father came to this country unable to read or write, from Austria," he said. "I have the original steamship ticket that they used for the whole family, but they changed their ages to get cheaper fares and God knows what, and my father didn't really know when his birthday was. He never made $100 a week in his life."

Dr. Weiss grew up on Kings Highway in Brooklyn.

"I always wanted to be a dentist, I have no idea why," he said. "When people said to kids, 'What do you want to be?' and they said fireman or cowboy, I said dentist. Everyone laughed, but I never changed my mind, and I've never been sorry."

A pioneering implantologist, Dr. Weiss has traveled the world and the Chrysler Building has been a calling card.

"I found out that this building is really the icon of New York City," he said.

To walk through the Chrysler's lobby, which is triangular, with entrances at each point, its fresco of compasses and biplanes and the brotherhood of workers above, is to understand its design as a crossroads, where the world would arrive and depart, where the myth of the 20th century was machined. On Tuesday, tourists lighted the marble cavern with camera flashes, like archaeologists who had found the Pharaohs.

Dr. Weiss appears to like exploring the building as if he were at home.

"Let's walk down and see if we can get into the Cloud Club," he said, on the service stairs, of the fabled executive dining club, dark and disassembled for many years. Dr. Weiss recalled lunches there in the 60's and 70's, when telephone operators still patched in calls with plugs into panels, like the first fast minutes of a romantic comedy, when cities throbbed with talk.