Construction on Edinburgh’s South Bridge was completed in 1788, and it soon became a bustling shopping street for those passing between the Old Town and the university. While crowds of people tramped atop the bridge, an underground world flourished in its shadows.

The bridge’s 19 arches housed various vaults and chambers originally used by the businesses that lined it. Cobblers and smelters used the subterranean spaces as their workshops, merchants stored their excess goods out of sight, and even the pubs served patrons drinks in the lower-level chambers.

But these legal businesses did not last long. In as early as 1795—not even a decade after the vaults opened—the shops began to abandon the vaults. The bridge hadn’t been properly sealed, leading to frequent flooding. The cold walls grew damp and musty, and insufficient ventilation made spending time in the dank chambers rather uncomfortable.

Once the original businesses moved out, a seedier crowd took over. Brothels, gambling pubs, and unlicensed distilleries flourished within the labyrinthine spaces, tucked out of sight of the above-ground world. Its believed body snatchers even used the cool, dark vaults to store corpses.

The rooms also served as housing for Edinburgh’s poorest residents, who crammed into the tight spaces. Entire families packed into the windowless chambers. There was no running water or sanitation, and disease ran rampant.

It has been estimated that there were somewhere around 120 of these dank and dingy vaults. Each capable of holding up to 20-30 persons. This would have put the population living in these squalid conditions around an estimated 2,000 to 3,000 inhabitants.

In the mid-19th century, the vaults were filled with rubble and sealed to displace those who dwelled within them. They remained forgotten until the 1980s, when the subterranean hub was accidentally rediscovered.

Today, you can book a tour of the vaults and experience this once-forgotten part of Edinburgh's history firsthand. You'll traipse the uneven terrain, illuminated only by flickering candles and the occasional burst of light from a handheld torch. The vaults are rumored to be among the city's most haunted spaces, adding to the unnerving atmosphere.