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The square board, the corners, the railways and the jail were all in a patent drawing from 1904. But Lizzie Magie's Landlord's Game was built to show what goes wrong when someone owns everything, not to make you want to.

In August 1911, crowds filed into the Louvre to look at four iron hooks on an empty wall. The Mona Lisa had been stolen, and its two years away did more for its fame than centuries on display.

From 1696 to 1851, England taxed houses by counting their windows, and some owners did brick them up. But plenty of blank windows were never windows at all, and the tax almost certainly didn't give us "daylight robbery".

Almost every interval on a well-tuned piano is very slightly off. That isn't the tuner's mistake. It's a long-standing compromise that lets one keyboard play in every key.

Every marathon is run over exactly 42.195 kilometres (26 miles 385 yards). That oddly precise number doesn't come from ancient Greece. It comes from one race in London in 1908, and the layout of a stadium.

Friday the 13th feels like ancient dread. But as a single superstition it doesn't show up in the record until the 19th century, and the famous Knights Templar origin story was attached much later.

The croissant looks as French as a café table. But its crescent shape comes from Vienna's kipferl, a pastry with a medieval record, and the famous story about a siege is a much later legend.

The push that drives a rocket happens between the rocket and its own exhaust. Outside air isn't what it pushes against, which is why empty space doesn't stop it.

Give randomly jiggling atoms long enough and, very rarely, they could fall into the shape of a single working brain, complete with memories of a life it never lived. Some models of the universe seem to predict far more of these lonely minds than ordinary people. Physicists don't take that as news about reality. They take it as a sign that a theory has gone wrong.

A gravitational-wave detector rests on glass mirrors hung at the far ends of long laser arms. Its real trick isn't sensing motion. It's stopping almost every other kind of motion first.

A lump of corroded gears from an ancient shipwreck turned out to be a calculator for the sky. What survives shows how it flagged eclipse months; how much more it once did is partly a modern rebuild.

Over a couple of centuries, the long vowels of English (vowel sounds held for longer than their short partners) moved, and the letters that spelled them mostly stayed put. For the most part the spelling didn't change to follow the sounds, so English spelling that looks wrong is often a record of older speech.