My good friend A posted this on Facebook. I watched it a few times in a row.
The video is of a tunnel boring machine breaking through and finishing the Airportlink tunnel in Brisbane, Australia. The time lapse ends with the burial of the machine.
It is cheaper to bury the used drill in concrete at the end of the tunnel then to bring it back to the surface. Its work finished, it becomes a part of the supports of that which it built.
The walls of a library are held in place by the books that built it. The history of a place becomes that place.