We visit the 'secret' vaults under iconic Bristol bridge discovered by accident

In 2002, contractors made an incredible and accidental discovery of secret vaults hidden beneath the iconic Clifton Suspension Bridge, built by Isambard Kingdom Brunel.

Two decades on and tours of the underground vaults are still as popular as ever, often selling out in advance. Using a platform built in the largest of the 12 chambers, the tours allow easy access and more people to witness the spectacle.

The Suspension Bridge might be the most iconic structure in the South West, but not many people know of the secrets that lie beneath.

Discovered accidentally in 2002 when contractors were repairing the pavement on the bridge above, Brunel’s vaults had been forgotten about and filled with rubble in the access areas for 162 years.

The rabbit warren of vaults includes 12 chambers of different sizes, although the deeper ones are only accessed with specialist safety gear and harnesses.

Few people know of the vaults, despite their discovery 20 years ago, or some people have a suspicion they are there but don’t know how to get into them or whereabouts they are.

Why are the vaults there and how were they found? The vaults are completely man-made by Isambard Brunel and his team of builders, and they were one of the first parts of the bridge that was constructed.

It exists because the people who were funding the bridge thought that his original design was too long and the two towers needed to be closer together, so this is the platform for the bridge tower to be put on top of.

It was built in stages up towards the top and the builders will have taken everything up with them as they left. So, when it was discovered, there was pretty much nothing in there.

Although engineers always thought they might be here, they didn’t expect them to be quite so huge. The chambers are now monitored and inspected every year, to see what the rocks are doing and how the structure is upholding.

So, what can youngsters (and adults!) expect from the tours? For years, children may have been used to taking a walk across the bridge but now they will have the opportunity to tell their friends and family about the inner workings of the well-known site.

To start, families are kitted out with a hard hat, before they climb down the ladder to the impressive underground echo chamber 11 metres high. Made up of lime mortar, with lots of calcium carbonate in it, the vaults have years of stalactites and stalagmites hanging from the ceiling, making for an incredibly beautiful and atmospheric visit.

The tour includes a sensory map to follow as you explore the largest and most significant of the twelve stone vaults. Expect a humid temperature of 12.5 degrees (this temperature stays constant all-year-round), and a lot of echoes, which only add to the unique atmosphere of the vaults.

With a deck that allows people to see more of the vaults than ever before, there is plenty to capture the interest of all ages while wandering around the underground chamber. From areas of danger and no access to sections that show the feat of engineering and 13 metre thick walls, the 40-minute tour will quickly pass.

Families will learn exactly how it was built. When you remind children that this was built during the Victorian times when there was no modern machinery, they will be even more in awe of a space like this.

The whole experience of putting on a hard hat and high vis, walking down the ladder and entering the secret space knowing that you are inside the Suspension Bridge is truly amazing.

Tours are suitable for ages 7+ and there is a minimum height limit of 1.2m. For more information and to book tickets, visit cliftonbridge.org.uk/family-friendly-vaults-visit/