I'm mapping street art in Berlin because it's my home city. Literally anyone in any city can do the same. If you will map street art in your city it will be cool.

I have made for this a crowdsourcing account-based map. Here you can read a bite-sized project description (link to download is at the end of the article) https://medium.com/@Goobkin/introducing-crowdsourcing-social-map-1715acf01a22