The Edinburgh underground vaults: what they are, and which tour gets you in

Edinburgh’s Old Town sits on a ridge running down from the castle, and the ground falls away hard on both sides. By the 1780s the city needed to expand south across the Cowgate ravine, and rather than level the hill it built a bridge over it: the South Bridge, begun in August 1785 and completed in 1788.

What makes it strange is that it does not look like a bridge. It has nineteen arches and exactly one of them is visible — the one that crosses the Cowgate. The rest are buried in the built-up ground on either side, with shops and tenements sitting on top of them. Walk up South Bridge today and you are walking on a viaduct that has been camouflaged as an ordinary street.

The arches were not left hollow. Builders formed roughly a hundred and twenty chambers inside them, ranging from about two square metres to about forty. That was the point: usable commercial space, right underneath the busiest new street in the city, at no extra cost in land.

It should have worked. It did not, for one reason that no tour guide has to exaggerate: the bridge deck above was never properly sealed, and there was no drainage below. Water came down through it. The chambers had no windows and no ventilation, so nothing dried. Within roughly thirty years the trades that had moved in were moving out again, and the record of abandonment starts as early as 1795.

The vaults came back by chance. In the 1980s Norrie Rowan — a former Scotland rugby international who owned property above the arches — broke through into the space beneath his building. What he found was a warren of stone chambers packed with rubble.

Excavation followed, and in 1985 it turned up the evidence that settled the question: middens of domestic rubbish. Oyster shells, bottles, plates, toys. Not storage waste — the debris of people living. That single finding is the foundation of every vault tour operating in Edinburgh today, and it is the reason a guide can tell you the chambers were inhabited without hedging.

It is worth sitting with how recent that is. Your parents were alive when nobody knew these rooms were down there.

The tours do not all enter the same chambers. Two entrances are in regular use: Blair Street, on the west side of the bridge, and Niddry Street, on the east. Both open into chambers inside the same structure, but different operators hold different sections under different arrangements.

Practically, this changes two things. First, your meeting point: Blair Street and Niddry Street are a two-minute walk apart but they are not the same door, and in the dark that matters. Second, if you have already done one vault tour and are considering a second, ask which entrance it uses — a different section is at least a different set of rooms.

What it does not change is the substance. Same bridge, same dates, same story, same temperature. Anyone telling you one set of chambers is materially more haunted than another is selling.

This is the single most common confusion in the city, and it costs people money.

The vaults are rooms inside a bridge. Nobody planned to live in them, they were never streets, and they have no daylight because they never had any.

The Real Mary King’s Close is a street. It ran down the north side of the Royal Mile like the dozens of others still there today, with houses on both sides and open sky above it. In 1753 the city built the Royal Exchange over the top of it, partly demolishing it and burying the rest. People carried on living in the surviving parts until 1902.

They are two separate sites, two separate tickets and two separate operators, about four minutes’ walk apart. One tour will not get you into both, and no listing will warn you that you have picked the wrong one.

None of this makes sense without the shape of the ground. The Old Town occupies a single ridge running east from the castle rock — a crag-and-tail formation left by a glacier, with the hard volcanic plug at the west end and a long tapering slope behind it. The Royal Mile runs down the spine of that slope. Everything else falls away.

To the north was the Nor Loch, a shallow polluted marsh that the city used as a dump and as a defence, drained from the middle of the eighteenth century and now Princes Street Gardens. To the south was the Cowgate ravine. In between, on a strip a few hundred metres wide, lived one of the most densely packed urban populations in Europe, stacked ten and twelve storeys high because there was nowhere else to put them.

By the 1780s the pressure was unmanageable and the city had two options: level the hill, or bridge the gaps. It bridged them. The North Bridge went over the drained loch towards the new Georgian grid; the South Bridge went over the Cowgate. Both were built to carry a street, not to look like bridges, and both were built up on either side until they vanished into the townscape.

That is the whole explanation for the vaults. They are not a secret and they were never intended to be mysterious. They are the inside of a piece of civil engineering that the city then hid, because hiding it was the point.