“Mysterious subway tunnels of some antediluvian civilization found?”

In the 1850s, the London authorities thought of an interesting project: an underground train. Later, this engineering marvel will receive an official name: the subway. The reason for the need to create an alternative way of moving around the city was traffic jams.
Unbelievable, but in the 1850s, London already had traffic problems on the streets. The large number of taxi drivers and the uncontrolled movement of city dwellers made it seriously difficult for riders to get to the right place at the right time.
The best minds have dedicated themselves to solving this situation. Some suggested using flying means like balloons, but it was too unsafe. Others wanted to introduce ministerial guards.
At that time, it was forbidden to appear on the streets of London for everyone, except for policemen and gentlemen who needed to quickly get to the right place. As a result, the engineers consulted and proposed an interesting project – the subway.
The city authorities reacted with great enthusiasm to this proposal. And construction began. True, there was no need to build a lot. Under London there was a network of tunnels acceptable for tube construction.
Archaeologists wanted to explore the tunnels, but city officials didn’t want to slow the pace of subway construction, and as a result, the discovered passages were never dated.
Who and when built them dozens of meters underground? It is not known.
English engineer and builder Geoff Stockers wrote about the construction of the London Underground: “It was decided by decision of the council to use the uncovered tunnels. This greatly simplified the task, as the vaults of the structures were perfectly reinforced with stones.
The actual task was to lay the lines and release the flooded area 35 meters deep from the water. As a result, the first metro stations will be operational much earlier than originally planned.”
A similar situation occurred during the construction of the metro in Moscow, St. Petersburg, Los Angeles, London, Rome, Madrid, Naples, Glasgow and other cities.
Some of the stations and tunnels, of course, were built from scratch, but the truth is that the old underground tunnels under the big cities were used to simplify project schedules.
Who built these ancient structures? If they were just tunnels for transporting people, why are they so big that a modern train can easily fit in them?
Antiquities researcher Graham Paul claims these excavated dungeons are tens or hundreds of thousands of years old. At that time, a technologically advanced civilization already existed on Earth. And these tunnels were an antediluvian pneumatic underground.
There is a hypothesis that history is cyclical and has repeatedly reached the peak of its development on our planet, but then fades and dies. It was its heritage that engineers of the 19th and 20th centuries used in the construction of the modern subway in several cities.
Think about it. Ancient people extracted millions of cubic meters of earth from the ground. The depth of these tunnels varies from 15 to 80 meters.
So… “Why did the ancient inhabitants of the planet need to build complexes of underground tunnels so complicated and so deep?”
Obviously, the reason was very serious, as the time and effort invested had to be equal to the problem that forced them to start building massively underground.
Was it a global cataclysm, a world war, or simply technological progress necessitated the use of underground space?