Vaults under South Bridge, a guided visit to the 18th-century chambers

Beneath South Bridge, the bridge built in the 18th century to link the High Street with the south of the city, vaulted chambers were left between its arches: the vaults. At first merchants used them as warehouses and workshops. In time they ended up as homes for the poorest, unlicensed taverns and hiding places for thieves. Today you can only enter with a guide, and two companies have access to different parts.

Two companies, two sets of vaults

Mercat Tours goes into the Blair Street vaults, which it presents as the oldest and deepest, and is the only walking-tour company with access to them. Its tours start at the Mercat Cross, on the High Street, take a walk through the old town and then go down into the chambers. They finish at its small vaults museum on Blair Street. They last 1 h 15 min and admit children from age 5.

Auld Reekie Tours goes through the vaults that open onto Niddry Street, also under South Bridge. It leaves from 300 Lawnmarket, in the upper part of the Royal Mile, and ends at its office at 45 Niddry Street. Its daytime tour lasts an hour and costs £24 per person, or £80 for a group of four. Inside they show a room that was used by a modern witchcraft group, with its stone circle.

By day for history, by night for ghosts

Both companies have a history version and a ghost version. The daytime one explains how the vaults were built and who lived in them; Mercat lets you touch objects found there. The night-time one focuses on crimes, executions and legends; Mercat warns that it does not stage scares. Auld Reekie does not admit under-12s on its night tours; Mercat opens its night tours from age 5. All are in English.

Inside it is cool and damp all year round, with uneven floors and steps. Wear shoes with grip and a jacket even if it is nice outside.