> Or some other steps were taken to prepare the (known) landfill for a heavy building, but nothing was done for just a plain tarmac? Yes: https://en.wikipedia.

> Or some other steps were taken to prepare the (known) landfill for a heavy building, but nothing was done for just a plain tarmac? Yes: https://en.wikipedia.org/wiki/Underpinning https://en.wikipedia.org/wiki/Underpinning