The Cannonball House: Beyond Preservation Purgatory

The Cannonball House in the way at the Southwest Treatment Plant. July 18, 1956. (
Detail of the Lower Schuylkill from Thomas Holme’s map of Pennsylvania, 1687. (The Library of Congress)

Peter Cock couldn’t have picked a more off-the-beaten track location for his farmhouse. In the 1680s, and for a long time after, nobody coveted the swampy rise that broke the horizon near the Schuylkill as it meandered to the Delaware. Why would they? With so much rich, dry land in every direction and with William Penn’s ambitious “green Country Town” drawing folks six miles upstream, these brackish bogs were, literally, a Swedish-settler’s happy backwater. But the site proved good for farming, and provided well enough for the next owner to expand the farmhouse. That brick house stood quiet and alone for the better part of the 18th century.

Then all hell broke loose on the lower Schuylkill.

With the American Revolution in high gear and the British occupation of Philadelphia underway, control of the city’s port meant that the British would need to take the American-controlled fort built downriver at Mud Island, just below the mouth of the Schuylkill. At Fort Mifflin, as the installation would become known, several hundred American troops were garrisoned. And for weeks they foiled British attempts to reach the city by river. In a siege that would be the largest the largest bombardment of the Revolutionary War, six British ships bristling with 209 cannon would overwhelm the American’s ten. Over five days with an estimated 10,000 cannonballs flying, the fens of the Schuylkill were quiet no more.

Nor were they safe. On November 11th, at the start of the siege, a cannonball entered the rear wall of the old farmhouse, passed through and exited the front wall. From that day forward, old Swedish farmhouse would carry a new name: the Cannonball House.

And for the next 219 years, the Cannonball House, a survivor that would eventually come to be considered the oldest house in Philadelphia, would be treated with veneration, deference, and respect. Artists would sketch it; antiquarians would photograph it; and the Historic American Buildings Survey would document it.

By the start of the 20th century, as the city’s population expanded and its farmland shrunk, the now city-owned Cannonball House served as a “model farm” until the demand for sewage treatment overwhelmed the need for demonstrative agriculture. And the Cannonball House quietly accommodated as the Southwest Treatment Plant enveloped it. When operations started in December 1954, 100 million gallons of sludge passed through each and every day.

As the bicentennials of the battle of Fort Mifflin and the birth of the nation approached (and the 1950s sewage plant grew creaky) Philadelphia’s oldest house became its newest problem. Expansion demanded more land. “I wish the British had done a better job,” the Water Commissioner confided to a reporter.

The Cannonball House in preservation purgatory, September 3, 1976. (

In 1974, the Philadelphia Historical Commission decided that the Cannonball House wasn’t important enough to be listed on the National Register. But it was too important to be demolished. The Commission urged it be moved to a new site across from the entrance to Fort Mifflin. And in 1975, the main section of the Cannonball House was lifted from its foundations and wheeled slowly down the road. The Environmental Protection Agency, expecting local follow through to finish the job, picked up the $168,000 tab. And for next 21 years, the Cannonball House was a house without a home in preservation purgatory. And Fort Mifflin had a historic headache in its would-be parking lot.

In this uprooted state, deteriorated and on temporary cribbing, the orphaned Cannonball House was unable to charm its way into even the preservation-inclined heart of Inquirer’s architecture critic, Thomas Hine, who put it in December 1981: the “Cannon Ball Farm House has little claim to our minds and hearts…it requires some bravery to choose to forget it.”

Forgetting would take place, but it wouldn’t be brave. One day, in November 1996, what the British didn’t do, what sewage engineers wouldn’t do, the city, in violation of its own review requirements, did do. They demolished the Cannonball House. Raw sewage got treated; historic preservation got mistreated; and Fort Mifflin got its parking lot.

One reply on “The Cannonball House: Beyond Preservation Purgatory”

You’re right, Ken. A complete failure of historic preservation, both regulation and motivation. It’s a testament to the durability of building construction that it lasted as long as it did on skids in the parking lot!

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