Sarah Pardee Winchester lost her only child in 1866 — Annie, six weeks old — and her husband William, heir to the Winchester Repeating Arms fortune, to tuberculosis in 1881. What she inherited was staggering: roughly twenty million dollars and an income stream from nearly half the company’s stock, at a time when the Winchester rifle was busily earning its nickname as “the gun that won the West.”

Legend says a Boston medium told her the spirits of everyone killed by Winchester rifles demanded a house — and that if she ever finished building it, she would die. The medium is almost certainly a later invention; no contemporary record of the séance exists. What is documented is strange enough: in 1886 the widow bought an eight-room farmhouse outside San Jose, California, and then did not stop building. For thirty-eight years.

The house that ate its blueprints

There was never a master plan. Sarah sketched rooms on napkins and tablecloths and handed them to her foreman; what didn’t work was boarded over and built around rather than torn down. The result, by 1906, was a seven-story labyrinth of more than 500 rooms constructed and reconstructed — staircases that climb directly into ceilings, doors that open onto brick walls or two-story drops, a window set into a floor, chimneys that stop short of the roof, and one staircase of forty-four steps that takes seven switchback flights to rise a single story, each riser just two inches tall (kind, as it happens, to a small woman crippled by arthritis).

And everywhere, thirteen: windows with thirteen panes, ceilings with thirteen panels, a chandelier altered from twelve candles to thirteen, thirteen bathrooms, drain covers with thirteen holes.

The 1906 earthquake brought down the top three floors and trapped Sarah in a bedroom for hours; workmen had to pry her out. She had the damaged sections sealed rather than repaired — another wing for the house to digest — and building went on. The popular story that hammers never stopped, twenty-four hours a day for four decades, is an exaggeration her biographer has punctured; crews came and went, and sometimes paused for months. But they always came back.

Two locks of hair

Sarah Winchester died in her sleep on 5 September 1922, at eighty-three. The building stopped mid-nail; workmen reportedly left half-driven nails in the walls. Her will — thirteen sections, signed thirteen times — left the fortune largely to charity and to her niece. Appraisers walked the house for weeks and got lost doing it.

Then they opened her safe. Inside: no jewels, no deeds, no rifle-fortune gold. Two locks of hair — William’s and baby Annie’s — and their obituaries, folded and kept for half a century.

That is the real answer to the mystery house, and it needs no séance. The endless corridors, the doors to nowhere, the perpetual sound of sawing: whatever the spirits wanted, a widow who had lost everyone found a way to make sure tomorrow always had a purpose. As long as the house wasn’t finished, neither was she. The house still stands in San Jose — 160 rooms, give or take; nobody has ever quite agreed on the count — and it is still not finished.