Stand at the foot of Main Street Southeast and look up. The great limestone hulk above the east bank of the Mississippi doesn’t announce itself anymore — no roar of rollers, no haze of flour dust drifting over St. Anthony Falls. But for forty years, the Pillsbury A Mill was the largest flour mill in the world. Every carved oak panel and ancient fireplace inside the Pillsbury Mansion at 100 East 22nd Street was paid for, sack by sack, in this building.

A Wonder Rises on the East Bank

Charles Alfred Pillsbury had bought his way into the flour business in 1869, a young man with more nerve than milling experience. Twelve years later he answered his own ambition in stone. Construction began in 1880; by 1881 the A Mill stood complete — a fortress of Platteville limestone roughly 175 by 115 feet, designed by architect LeRoy S. Buffington and raised under contractor George McMullen. It is still considered a classic of American industrial architecture, a mill built with the confidence of a cathedral.

The “A” meant exactly what you’d guess. This was the flagship — the mill against which every other Pillsbury property, and eventually every mill on Earth, would be measured.

The Power of the Falls

Beneath the mill, tunnels carried diverted river water to two of the most powerful direct-drive waterwheels ever built — each capable of some 1,200 horsepower, all of it borrowed from St. Anthony Falls, the only major waterfall on the entire Mississippi. The A Mill opened producing about 5,000 barrels of flour a day and eventually pushed past 17,000. For four decades, nothing on the planet out-milled it. This was the engine of “Mill City,” the era when Minneapolis fed the world.

The industry’s dangers were never far away — three years before the A Mill opened, an explosion of flour dust had leveled the rival Washburn A Mill across the river and killed eighteen men. We told that story in The Great Mill Disaster of 1878; Pillsbury’s engineers built their new mill with its lessons burned into memory.

From Mill to Mansion

Follow the money from those grinding stones and it leads, a generation later, to a quiet corner of East 22nd Street. Charles Stinson Pillsbury — son of the founder — used the fortune the flour empire created to complete his Elizabethan manor in 1916, filling it with genuine centuries-old English interiors gathered by the dealer Charles of London. The A Mill ground the wheat; the family turned the proceeds into one of the most extraordinary houses in the Midwest.

What Became of the Great Mill?

The A Mill ground on for an astonishing 122 years, finally falling silent in 2003. It was named a National Historic Landmark back in 1966, yet by 2011 it had landed on the National Trust for Historic Preservation’s list of America’s most endangered places. Salvation came in an unexpected form: developers converted the complex into the A-Mill Artist Lofts, opened in 2015, with a new hydroelectric turbine spinning in the very tunnel that once powered the millstones. The Library of Congress preserves a full architectural record, and Minneapolis Historical tells more of the mill’s story.

See Where the Flour Fortune Landed

The A Mill still stands above the falls — but the fortune it ground out lives on at the Pillsbury Club. Come walk the halls the flour built: Minneapolis Trolley Tours departs from the mansion itself, and if you’d like to sleep inside a Gilded Age fortune of your own, our sister mansion 300 Clifton keeps a room ready.

Keep reading: meet the man who ran the mills — Philip Pillsbury, the master miller who grew up in the mansion.