The Ballad of the Walled-Up Wife chronicles the story of hapless masons who are incapable of building a wall that will last. After years of failure, they learn that in order to make their work last, they must offer up a sacrifice. Once, as their master’s wife passed by, they grabbed her and entombed her in the wall they were building. According to some versions of the ballad, the wall still stands.

While immuring wives in walls is strictly outlawed (and largely fictional), the practice of hiding things behind sheetrock or brick is pervasive. From the illegal to the superstitious to the just plain insane, here are 9 crazy things found stashed inside walls.

1. Babies

In 1850, a mummified baby tumbled out from between the walls of a Parisian apartment. The couple living in the apartment were charged with murder; they were later cleared when a physician used insects to determine the time of death. This case marked the first time in French forensic science that entomology was used in a criminal trial. And 28 years later, French pathologist Edmond Perrier Megnin used insects to calculate the time of death of a mummified infant in a similar case.

Mummified infants have been found in walls as recently as 2007, when contractor Bob Kinghorn discovered the body of a child wrapped in newspaper in the walls of a home in East Toronto. Police investigated the infant’s death, but were unable to determine the cause.

2. Urine and Fingernail Clippings

Filled with urine, hair, nail clippings or red thread, Witch Bottles were hidden in walls and buried in the thresholds of homes to counteract a witch's curse. One was found in Greenwich in 2009 that dates back to the 17th century. Researchers were even able to analyze urine found in the bottle, which contained traces of nicotine.

The bottle also contained a piece of leather cut into the shape of a heart and pierced with a leather nail. Scientists are unsure of the symbolism, but in similar finds the bottles have contained heart-shaped cloth pierced by brass pins.

A court record from 1682 documents that a husband who believes his wife to be a witch should boil in a pipkin a quart of her urine, fingernail clippings and hair.

3. Live Children

Two years after he disappeared with his mother, 6-year-old Richard Chekevdia was discovered hidden in the walls of his grandmother’s home in Illinois.

Ricky disappeared in 2007 after a contentious custody dispute between his mother, Shannon Wilfong, and his father, Michael Chekevdia. His grandmother, Diane Dobbs, insists that the boy lived most of his life outside the walls of the home, only hiding when necessary. However, police reports state the boy had rarely been allowed outside. And a judge found that the boy had been denied access to medical care, education and contact with his peers. The police found the boy and his mother crouched in a hiding place behind a bedroom dresser.

4. Cash

In Ohio, contractor Bob Kitts found $182,000 in Depression-era money inside the walls of a bathroom he was renovating. The contractor called the homeowner, Amanda Reece, who offered him 10 percent of the find. He demanded 40 percent and the situation devolved from there.

When the Cleveland Plain Dealer reported on the case, descendants of the home’s original owner, Patrick Dunne — a wealthy businessman who hid the money during the Great Depression — also filed claim to the money. After the costly court proceedings, all of the people laying claim to the money received only a fraction of the find.

5. Priceless Artwork

In 1502, Italian statesman Piero Soderini commissioned Leonardo da Vinci to paint a scene from the famous Battle of Anghiari. The painting is thought to be 20 feet long and 10 feet high. In the 1550s, Giorgio Vasari was commissioned to paint over the mural, but the painter reportedly couldn’t bring himself to destroy it.

Maurizio Seracini, an art diagnostician at the University of California, San Diego, has been looking for the lost Leonardo da Vinci work for 36 years. Seracini is convinced that Vasari hid it in the wall — and he might be onto something.

His first big break came in 1970, when he discovered the words "cerca trova” painted on a flag on Vasari’s mural. Seracini believes that the phrase, which means “seek and you will find,” indicates that Vasari built a false wall over the painting in order to preserve the mural. Recent technology has enabled researchers to take pictures of the hollow between Vasari’s mural and the wall, where they discovered black pigment believed to be similar to the pigment used in other Leonardo da Vinci paintings. Unfortunately, bureaucracy and political protest have stymied the investigation.

6. Ill-Gotten Gains

In the walls of his home in Oak Brook, Illinois, mobster Frank Calabrese hid jewelry, fire arms and, of course, cash money. Lots of it.

During Calabrese’s 2007 trial, authorities learned that the long-time hit man liked to stash money and weapons into the nooks and crannies in his homes. After the trial, federal agents procured a search warrant and discovered Calabrese’s stash of loot and taped recordings with other mobsters behind the basement’s wood-paneled walls. Calabrese’s lawyer told the Chicago Tribune that he was “concerned” that these items hadn’t been discovered in previous searches of the home.

7. Shoes

A collection of 300-year-old shoes was found in the wall of the Gothic Liedberg Palace in Korschenbroich, Germany. In Lubenham, England, a pair of shoes was built into the wall of Papillion Hall in order to rid a family of decades of misfortune brought on by a curse. And in cottages and churches across Europe and the United States, hundreds of shoes have been found tucked inside the walls. The practice is so common that the Northhampton Borough Council collects recorded instances of concealed footwear. If you find any, let them know.

Some scholars theorize that the practice of immuring shoes is done for good luck and to ward off evil spirits from entering a home.

8. Cats

The practice of hiding cats in walls was an ancient ritual to ward off evil spirits. All over the UK, mummified cats are frequently toppling out from between the walls of 17th and 18th century buildings. One of the most famous instances was in Pendle, Lancashire, when a mummified cat was discovered in the wall of an ancient cottage. The cottage is presumed to be the location at which one of England’s most famous witch covens met. In 1612, 11 men and one woman from the coven were accused of witchcraft and hanged.

9. Unmentionables

The only thing worse than discovering dirty underwear hidden in your home is discovering centuries-old dirty underwear in your walls. Across Western Europe, unsuspecting home owners often find caches of garments (under and over) inside the walls of their homes. In fact, the finds are so common that they are not often reported.

Evidence indicates that the practice of hiding your knickers in the walls dates back to the Middle Ages. The clothes hidden are often worn and contain hidden objects like documents and coins. According to the website for the Deliberately Concealed Garments Project: