Once, in a passing chat with the concierge in my Paris apartment building, I learned that a tenant—who had lived in my unit for decades—was a mistress of the great singer and actor Jacques Brel. He called on this woman in the early 1970s at her apartment in northeast Paris, in the old Quartier du Combat, and took her out on the town. Where did they go? The concierge couldn’t say. Once they left the building, they were beyond her realm.

These charming tête-à-têtes are vanishing with the decline of the concierge profession. Concierges, or gardiennes, have long guarded the grand Haussmann buildings of Paris. Mostly women and often gimlet-eyed, they were fixtures of city life, immortalized by artists such as Jean Béraud and Gustave Caillebotte, who painted them sweeping doorsteps or peering from their ground-floor apartments. The novelist and playwright Honoré de Balzac depicted them in his literary series “La Comédie Humaine” (1827–1848) as meddling figures, privy to their tenants’ secrets. In the 20th century, municipal authorities began awarding concierges for their dedication to maintaining buildings and serving tenants with unwavering vigilance.