They are the white-gloved sentries, standing guard at New York City’s better addresses, so signature a feature of life here that we tend to forget that in other metropolitan centers like Paris, London, Chicago or Boston uniformed doormen (and, less often, women) barely exist.

They form a small army, some 35,000 residential doormen, concierges, porters, handymen and supers represented by a powerful union, 32BJ. They open doors, of course, load cars, receive packages, pass dogs off to professional walkers and in general make themselves indispensable to an ease of life many in this demanding town take for granted.

Yet as protectors of the border between public and private, doormen play a role crucial to the currents of the metropolis, one never more evident than now when the front line of a global pandemic is one’s threshold.

“Yes, it’s a job, but we also try to keep the building as a home,” said Alberto Ventura, 65, who has worked the door at the same Park Avenue building for 42 years. “With the virus, we’re trying to take it a day at a time and be as calm as we can.”