Mercat Tours, which curates the Blair Street Vaults in Edinburgh’s Old Town, says the city’s violent history hands ghost tours a ready-made story. Underground, its general manager says, the dark does the rest.

The BBC found the vaults candle-lit and gloomy, and silent apart from nervous coughs. On its visit a woman hurried out partway through because the tour had unnerved her.

Why the vaults work, according to the people who run them

Shirley Suliman of Mercat Tours calls the city’s past gory, from grave robbers and torture to murder at Holyrood Palace. Fear does not always need blood, she adds. In the Blair Street Vaults, she says, the lack of light is enough to get hearts racing.

The vaults have their own stories too. Time Out says several ghost tours run in the underground vaults, and that people have reported a range of paranormal activity there. The TV show Most Haunted broadcast a live investigation from the vaults in 2006. Some accounts say Burke and Hare kept their victims’ bodies there before selling them to the medical school, Time Out adds.

The Banshee Labyrinth, a pub that sits partly inside the vaults, bills itself as Scotland’s most haunted pub.

A habit with a name

Visiting places tied to death has a label. Professors John Lennon and Malcolm Foley coined “dark tourism” in 1996. Lennon, of Glasgow Caledonian University, says death is common to everyone, which is why people are drawn to sites of suffering.

Edinburgh offers plenty. The BBC found it close to impossible to walk the Royal Mile without meeting a ghost walk or a Burke and Hare tour. The Necrobus, a black 1960s Routemaster, tours the streets after dark.

What else lies below

The vaults are not the only way down. National Geographic Traveller lists The Real Mary King’s Close, where people of the 17th century lived and worked underground, alongside a tour of the vaults. The BBC notes that the close, though billed as social history, still features murders, plague victims and executions.

Above ground, Greyfriars Kirkyard keeps an iron mortsafe over two graves to deter bodysnatchers such as Burke and Hare.

Who comes

Edinburgh drew 3.5 million visitors in the year before the BBC report, second only to London among UK destinations. In 2013 a sixth of its overseas visitors came from the US. One Californian on the Necrobus told the BBC the not knowing was what made it “creepy, scary and exciting”.

No source settles whether the ghosts are real. The tour operators do not need them to be.