Over the course of its existence, the Grimm building also housed a milliner’s shop, a tearoom and, in the 1950s, the rehearsal studio and offices of the avant-garde Living Theater.

The sociologist Ray Oldenburg, in “The Great Good Place,” a book about diners and taverns, suggests that the past is an essential element of all third places, which are usually in older sections of cities, and in those areas “exists the fading image of the city itself and the kind of human interaction, the easy and interesting mixing of strangers that made the city what it was.”

But not only what it was.

One of the charms of the Metro, and of many other diners in the city, is that the employees’ backgrounds are as varied as the languages spoken by the tourists who have found their way here. Costa Rica, Ecuador, Greece, Mexico, Poland, Romania — these are just a few of the countries where staff members come from. Together they constitute a microcosm of the immigrant groups that continue to arrive in New York — who not only made the city what it was, but the best of what it is and could be.

My first diner nesting place was Harvey’s Coffee Shop on 78th and Broadway, in Manhattan, where I would order matzo ball soup and a Coke after seeing my therapist across the street. Harvey was known for his Yiddish-speaking Puerto Rican countermen and for serving deliciously seasoned chopped meat on white bread.

After Harvey’s closed, I moved to the Utopia on 73rd and Amsterdam, a venerable place with a low ceiling, Greek-themed murals and waiters who seemed to never age. As my thighs outgrew the narrow booths, I moved to the Central Park Cafe/Restaurant, at 97th and Columbus.