Apartment 6J at 225 East 57th emerges as a secret retreat, sheltered in the building’s rear facing south so that Midtown’s hum becomes a distant lullaby. Inside, the proportions feel cinematic: the bedroom once cradled both a king-size bed and a grand sofa, yet still beckons you to carve out a second chamber or a quiet study. In the living area, an abundance of closets—deep, well-appointed niches—...