A historic townhouse holds details that cannot be ordered from a catalog. Carved mantels, stained glass, parquet and turned balusters were all handcrafted over a century ago.

Most homeowners measure a renovation by what happens on site. Walls come down, floors go in, cabinetry arrives. Yet in New York City, the schedule is rarely decided during construction.

For years, residential design moved toward openness. Kitchens joined living rooms, walls disappeared, and uninterrupted sightlines came to define contemporary interiors.

A new bathroom always looks right on the day it is finished. The tile is clean, the grout is bright and every fixture works. The real test comes later.