There are other interesting constructions under the ground in London.

While I was working at the old Ministry of Agriculture, Fisheries and Food on Horseferry road in the Westminster area of London, I was kept amused by the building of the three towers which were to become the HQ of the then Department of Environment. I was 18/19 years old then.

It was rumoured that the foundations of these buildings were in fact the WW2 air raid shelters of the Houses of Parliament (just up the street) . The shelters were apparently connected to the former by one or more tunnels.

Anyway, the good news was that these huge old underground shelters were also being totally refurbished for a new purpose.
They were going to be the new main Civil Service leisure facilities for central London....and right across the street from my office.

Included would be snack bars, restaurants, DISCO, pub, indoor tennis courts, snooker tables, etc etc. Open from mid-morning until late at night.

And so it came to pass, and my previously boring lunch hours were never the same again.