1936 Catalonia during the Spanish Civil War organized an Anarchist society with over 3 million participants, and they documented much of how exactly they ran it, right down to how they kept the electric trams for public transport going (there is a fantastic book embedded at the bottom of that article, Collectives in the Spanish Revolution by Gaston Leval, which offers more details on other aspects of how they operated that society).

It’s a fantastic historical event we can learn from and build upon, and it bore out quite effectively that a decentralized society functions quite well.