Flatiron, Gramercy & Union Square

The Flatiron Building has no apartment deeds, but the blocks around it have become one of the most built-up residential districts below 34th Street: One Madison and Madison Square Park Tower at 45 East 22nd, the NoMad trio of Madison House, Rose Hill and 277 Fifth, and the Zeckendorf Towers over Union Square, the condominium that remade the square in 1987.

Gramercy Park keeps its own records: 18 Gramercy Park South, sixteen full floors with keys to the gate. To the east, Kips Bay Towers is I. M. Pei's concrete pair from 1965, among the oldest condominiums in the city.