I was invited as a resident to a place called ZK/U and I used the time to write a full 'SCENARIO about the Open Source Circular City' that is meant to inspire Hacking our Cities for Circularity!
The Scenario has a lot of ideas and concepts for hacks you can implement right away. Please check the link:
Some ideas from it
Slow down traffic (scenario layer 4 'mobility')
Get rid of cars and repurpose the space for circular activities (layer 5 'people')
Transform the city into a botanical garden (layer 3 'nature')
Turn every building into a farm scraper (layer 7 'buildings')
And here is an invitation on our Forum to hack your city!