The water around Ramsey was drained in the 1850s
When it comes to the Victorians and underground construction the London Tube immediately springs to mind.
But a much smaller set of tunnels under the town of Ramsey has had a curiously under-appreciated history.
Keith Sisman has been keeping an eye on the condition of the tunnels since he was a child in the 1960s.
He told BBC Radio Cambridgeshire: "Father used to go down there with the fire service and the police. It is quite fascinating and quite unique."
These tunnels, that allow the Bury Brook to flow through the town, have existed below the feet of Ramsey's residents since 1854 without much of a fuss being made.
Those who know their Fenland history will be aware Ramsey was an island until Holme Fen was drained in the 1850s when water travel was being superseded by trains.
To meet the lower water level around the town three arches, or culverts, were built to allow the brook to safely flow underneath.
It was a great idea at the time but back then nobody envisioned the huge weights that would repeatedly crash down the Great Whyte, Ramsey's main thoroughfare.
Keith explained: "There's a terrific amount of weight that sits on the culverts.
"We have all that modern traffic going up and down the Great Whyte which of course the Victorians never thought of."
Keith takes the time to travel down into the darkness whenever he can to check on the structure's condition.
While there is no immediate possibility of the arches giving way, the result would be catastrophic.
"Where the clock tower is the culverts are sufficiently deep enough to have a double-decker bus drop through the road and completely disappear," said Keith.
Keith is quick to point out that the tunnels shouldn't be explored by curious visitors.
He always enters with a large group and carries a gas detector and bright torch.
There's also the threat of being caught under there when a downpour of rain hits.
Keith said: "Ramsey is quite unique to have a river running under the town, the water does go right to the foot of the culverts when there's been flooding."
The tunnels should never be entered without an expert
There are a few curiosities to the tunnels.
It is possible to stand right underneath some of the banks on the Great Whyte and legend has it that a brick wall was put up after a failed attempt to break into Barclays Bank from below.
The town clock, which is now operated by electricity, was once powered by the water that ran beneath it.
"It had a mechanism with a paddle at the bottom that was wound up by the water flow going through the Great Whyte," Keith said.
It's hard to believe that when the waters were at their highest Ramsey homed a bustling fish market selling eels down the river.
Now the waters that created so much industry trickle quietly beneath the modern hum of engines and shoppers.