Winchester-based Experience Hampshire, in collaboration with Southampton City Council and See Southampton, has been running the tours for more than two years.
The vaults were originally built during Henry II’s reign to store wine.
The two-hour guided tours take place under the city streets four times a week.
They have proven to be a hit, with more than 1,000 bookings so far.
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Winchester-based Experience Hampshire collaborated with Southampton City Council and See Southampton for the tours (Image: Experience Hampshire) Experience Hampshire’s chief experience officer and co-founder Roger Walker said: “I was fascinated to discover just over two years ago that there were a number of underground vaults, built during the reign of Henry II to store wine, right under the streets and buildings of the city.
“We have teamed up with Southampton City Council, who own and manage the vaults and See Southampton, whose expert guides lead all of our walks, to promote a two-hour tour which visits some of these vaults.
“They are so popular that we have received over 1,000 bookings to date.”
The tours run on most weekday evenings, Monday to Thursday, starting early evening from the Bargate.
Those interested in booking a spot on the tour can do so through the Experience Hampshire website.