The museum stood behind the tram depot, in a brick building that had once sorted mail and then, for twenty years, had sorted nothing. Its sign was modest enough to miss:

MUSEUM OF USEFUL MISTAKES

Visitors expected a room of blunders: bridges that had fallen down, menus with unfortunate translations, famous photographs printed upside down. There was a little of that. The curator had a fondness for the charming error, and one display case contained a municipal map on which the river had been accidentally labelled Public Avenue.

But the museum’s real collection was less funny.

It kept the first draft of the city’s street names. The old hospital plan that showed a maternity ward where the pharmacy now stood. A grant application calling a vacant lot “a future garden,” written six years before the garden existed. A bus schedule that still stopped at a factory demolished before most of the current passengers were born.

The labels did not mock the people who had been wrong. They named what the error had made possible.

THE PROPOSED GARDEN, 1998

The applicant underestimated the drainage work by eleven months. The application established a public claim on the land before it could become a car park.

THE FACTORY BUS, 2007

The route remained in print after the factory closed. Former workers used it to reach the employment office. A new route was later built on their travel pattern.

The curator, Mara Venn, said a mistake was useful when it left evidence of an intention worth recovering.

“This is not a museum of excuses,” she would tell school groups. “It is a museum of receipts.”

The city council disliked that sentence. Councils preferred a correction to arrive cleanly, without the embarrassing garment of its predecessor. Each department had developed a habit of replacing a document as soon as it changed. Old webpages disappeared. Planning maps were redrawn. Public notices were refreshed until they looked as though they had always known what was going to happen.

It was tidy. It was also, Mara argued, a way of making public life impossible to read.

One spring, the city announced a new pedestrian square beside the river. Renderings appeared overnight: white paving, young trees, café tables, a family whose happiness seemed to have been assigned by a committee. The old road would close in June. The square would open in October.

The launch went well. The mayor stood before a large image of the project and said the city had listened.

A week later, Mara received an envelope without a return address. Inside was an earlier plan. The square had once included a covered shelter, public toilets, and a row of low-cost kiosks for market traders. In the revised image, all three had vanished.

Mara did not rush to announce a scandal. Cities altered plans for good reasons as often as bad ones. The problem was smaller and stranger. The city had presented its final drawing as though there had never been another argument.

So the museum made a display.

It put the two plans side by side, neither enlarged, neither captioned with outrage. Between them it placed a blank card and a pencil.

WHAT CHANGED?

For three days, nobody wrote anything. Then someone added: A place to sit out of the rain. Another person: A place to sell things without paying restaurant rent. Someone else wrote: Maybe the toilets were too expensive. Say that, then.

By the end of the month the card had been replaced nine times.

The council asked Mara to remove the display. She asked them to send the reasons for the changes, and promised to place those beside the plans. They declined. A local paper printed a photograph of the blank card. It was, briefly, the most discussed image in the city.

The shelter returned to the plan in a smaller form. The kiosks did not. The toilets were replaced by an agreement with the library across the street, which was less elegant but more useful than nobody saying anything.

At the square’s opening, Mara stood at its edge in light rain. The paving was still too bright. The young trees looked as if they had been delivered that morning, which they had. Under the shelter, two teenagers ate chips while an older man studied a timetable with the stern concentration of someone who had earned a right to distrust it.

Mara thought of the museum’s first object: a handwritten error on an eighteenth-century street register. The clerk had crossed out Blind Lane and written Lantern Street. In the margin, another hand had added, because the lamps were installed after complaints.

That was all. No grand theory. No claim that the city had been redeemed by paper.

Just the old name, the new name, and the reason somebody had finally changed it.