For a country this small, Malta’s home to a jaw-dropping number of historical artefacts – and by some miracle, we keep finding new spots to dote over every year.

The latest historical spot to make waves internationally was none other than Valletta’s mysterious 16th century underground tunnels.

Don’t worry, we didn’t know there were tunnels under Valletta either.

On an episode of the Science Channel’s Underground Marvels, Heritage Malta Architect Ruben Abela and Malta Underground NGO Founder Mark Zimmerman gave the world a glimpse into these meticulously carved tunnels.

These tunnels came to be some 450 years ago, when the Knights of Malta dug a huge water reservoir under Valletta. Over the years, many more reservoirs, tunnels, and sewers were carved, thus creating what is nowadays a fantastic subterranean maze.

“These are actually two hundred years older than the London sewer system,” Ruben told the Science Channel.

But the Knights’ work didn’t stop there…

According to Express, the Order went on to carve out food and water caches under the city, ensuring access to vital resources should the city ever fall under siege.

And once that was done, Valletta’s residents took to the tunnels to build businesses and subterranean dwellings.

Credit: Valletta Underground

Years later, in 1881, a project to connect Valletta to Mdina via an underground railway was commenced, and thus “construction work began on a mostly overground line that also included two significant tunnels,” Mark Zimmerman said.

The line, which ran for a total of 11km, had a 1.5km section running underground. To give you some perspective int how revolutionary this was, the London Metropolitan, that is the first-ever underground railway line, had opened just 20 years earlier!

So next time you head to Valletta, remember that you’re quite literally walking on top of a slice of history.