This was covered in another thread about the hanky in a picture which had a piece of paper under it that had the words "Moloch Maschine". Same reference.

There's also an earlier scene where a group of poor children ascend from the depths into the "eternal gardens", where the "club of the sons", the adult children of the elites, dwell.

The Occult Symbolism of Movie “Metropolis” and its Importance in Pop Culture