You might enjoy learning about guifi.net.

TLDR: ISP didn't want to develop network infrastructure in a rural area of Spain. Citizens took matters into their own hands and started building a network mesh to bring connection from the nearby cities onto the area by connecting between individuals. After a few years (and surviving several pretty immoral lawsuits from the ISP) the network is +35.000 nodes strong and has extended its reach well beyond the original intended area.

A great example of decentralized, grassroots building.