20 Ingenious Ways People Guarded Their Homes Before Modern Security Systems

According to the Roman historian Livy, the alarm that warned Roman soldier Marcus Manlius of a stealthy attack by the Gauls on Rome’s Capitoline Hill around 390 BC came from an unlikely source: sacred geese. Geese have excellent eyesight and hearing and are extremely protective of their territory, so they squawked and flapped, warning Manlius of the Gauls. Unlike dogs, geese cannot be bribed with food, which certainly worked in Rome’s favor that night.

The entry corridor of a Roman townhouse housed a powerful mastiff-type dog that could confront any visitors making it past the door. The dog was chained, as shown in the famous CAVE CANEM (“beware of the dog”) mosaic, which depicts a snarling beast. It survived at the House of the Tragic Poet in Pompeii after the eruption of Vesuvius in 79 AD.

The caltrop was originally a weapon employed on battlefields. Cautious estate owners spread them along paths and at perimeter boundaries. The caltrop was made of iron and had four spikes, so it always landed with one spike pointing up, ready to pierce the shoe or bare foot of any trespasser before they got the chance to reach the front door.

The floors at Kyoto’s Nijō Castle, built in 1603, famously chirp underfoot. Legend has it that shoguns designed them to alert the palace to intruding ninjas, but studies and historical sources suggest the sound results simply from friction between iron nails and inverted V-shaped metal clamps. As the castle’s wood aged, this friction created an effective, if unintended, security system.

You’ve probably seen scenes in movies where defenders are pouring boiling oil down onto attackers. This is mostly a myth, as oil was very expensive and was more usefully kept for food and fuel. From the 11th to 15th centuries, castles and manors sometimes had so-called “murder holes,” or openings in the vaulted ceilings of gateway passages, allowing defenders stationed upstairs to drop large stones, hot sand, pitch, or scalding water on attackers.

A portcullis was a heavy gate made from a grid of iron-clad oak beams, sometimes weighing several tons. When the winch brake was released, it would plummet under gravity through a channel in the stone walls of the gatehouse and seal the entryway in seconds. These portcullises were often pointed at the bottom and were used on castles and fortified manors for centuries.

Some old entry doors were secured from inside with an enormous wooden beam that slid from a channel in the wall into a socket on the opposite side. Deep masonry channels beside surviving doors are historical clues that such beams, sometimes strengthened with iron, were used this way. In such a system, the energy of a breach was transferred directly to the masonry, so that breaking in would require not just breaking the door, but breaching the wall itself.

Between the 17th and 19th centuries, homeowners in Britain and colonial America hid glass or stoneware bottles filled with pins, iron nails, and organic matter under hearths, thresholds, or window sills as a form of folk protection against witches and other supernatural threats. Archaeologists have unearthed dozens of intact “witch bottles” like these.

During the 18th and 19th centuries, builders would mix broken pieces of glass bottles into wet lime mortar, which they used to coat the top of boundary walls. The mortar would harden, leaving behind a razor-edged surface that would lacerate anyone who tried to climb over it without tools or protection.

Rejas, heavy wrought-iron grilles or cages, covered ground-floor windows in Spanish colonial homes. Intruders could be kept out, but light and air passed through the rejas unimpeded. Blacksmiths hammered the rejas by hand and bolted them firmly into the masonry surrounding the windows from the 16th to 19th centuries.

From the 16th to 18th centuries, European locksmiths based in cities such as Nuremberg and Augsburg hand-forged intricate iron locks designed to make life difficult for anyone who didn’t know their tricks. Some had false keyholes hidden under decorative plates or fake rivets, while others had spring-loaded studs that had to be depressed in the correct order to reveal the actual lock. If someone found the wrong keyhole and inserted a key, the lock would jam shut.

The tops of the walls of some 18th- and 19th-century estates were adorned with spiked iron rods on a loose bearing so they were free to rotate. The spikes by themselves made climbing difficult enough, but when a climber grabbed the barrier, their weight turned the axle, and their hands could slide free.

Lethal spring gun traps, consisting of flintlock or percussion guns attached to swivels and triggered automatically by a tripwire, were used throughout the 18th and early 19th centuries in Britain. The trouble was that a tripwire couldn’t exactly tell a trespasser from a servant. After the traps frequently injured servants or other bystanders by accident, Britain’s Parliament passed the Spring Guns Act in May 1827, restricting their outdoor use.

After lethal spring guns were restricted outdoors, inventors of the mid-19th century produced a blank-firing alarm gun. Built of solid iron or brass, with just a chamber for a blank cartridge or a charge of black powder and no barrel to propel a projectile, the alarm gun was triggered by a tripwire. This activated a spring-loaded hammer that struck the percussion cap and made a great noise, solely to awaken the household rather than fire a shot.

Night watchmen and householders in the 18th and 19th centuries could raise the alarm with a simple hardwood rattle. When swung, the hardwood tongue struck a notched cogwheel, making a loud clattering noise that could be heard for several city blocks, summoning neighbors and the night watchman to the scene of trouble.

In 18th- and 19th-century households, a home’s burglar-alarm system could work entirely mechanically: fine copper or iron wires were stretched across doors and windows and were connected via brass pulleys and concealed passages in the walls to the master bedroom, where a spring-loaded bell-striker would sound a brass alarm bell whenever a wire was tripped, continuing until someone checked it out.

The Detector Lock, invented by British locksmith Jeremiah Chubb, could do more than resist a lock pick; it could tell the owner that someone had tried. The lock used a lever-tumbler design. If any lever was lifted too high by a lock pick, a detector lever caused a spring latch to trip, fully jamming the deadbolt. Once tripped, the lock would not open with the actual key, which indicated to the owner that it had been tampered with. Chubb patented the lock on February 3, 1818, following a burglary at Portsmouth Dockyard. It remained unpicked until 1851, when American locksmith Alfred Charles Hobbs finally cracked it at the Great Exhibition.

Augustus Russell Pope of Somerville, Massachusetts, was granted U.S. Patent No. 9,802 for an electromagnetic home alarm on June 21, 1853. Opening a protected door or window completed a battery-powered circuit, which then energized an electromagnet that repeatedly struck a brass bell. Although the original unit was built by Pope, businessman Edwin Holmes bought the rights to the device in 1857 and turned the patent into a substantial business in Boston and New York.

Eventually, home alarms could alert someone outside the house, too. Door or window sensors were hooked up via overhead wires to a 24-hour central monitoring station. When a contact was breached, it was indicated on a ticker board in the station, and an attendant ran to the location of the trouble. The first central alarm monitoring station was opened in New York City in 1877 by Edwin Thomas Holmes, son of Edwin Holmes, the businessman who had commercialized the electromagnetic home alarm decades earlier. The system was based on a telegraphic call-box system invented by Edward Calahan and patented in 1871.

From the 1920s through the 1950s, some safe manufacturers would install sealed glass vials filled with pressurized chloracetophenone, otherwise known as CN tear gas, behind the lock plate in the safe’s door. If a burglar attempted to drill, punch, or blast the lock mechanism, they could break the vial and release the gas instead, temporarily blinding and incapacitating them.

This content was created with the help of AI.