OSGwrote:
For the 3D metropolis token, this bonus is only awarded to the defender, and is in no way conditional on an attacker taking the metropolis. During our many test games, we were able to play several options, all of which lead back to the decision we've outlined for you. The metropolis token is placed face-down after its recipient has taken it, for an optimal view of Miguel's proposed graphics of the buildings that make up the metropolis. For the version with 3D buildings, we offer an alternative solution with a smaller token which is inserted under the metropolis sculpture when the bonus is taken. This token will be small in size, and you'll be able to choose the best way to use it during your games. You can place it next to the metropolis, or even above the port, so that you can see it constantly. Of course, this will spoil the marvellous sculpture Rodrigue Hubert has made for you.
I wanted to recal to all of you that you can test the game on tabletopia and see by yourself the utility of this bonus and its applications.