Fab City Challenge is an initiative launched in 2014 by the then mayor of Barcelona, challenging cities to become self-sustainable by 2054. The project has now expanded into a sustainable cities network working on the digital transition, localisation and regenerative economy. One focus is combating food waste and using fresh produce which would otherwise have been thrown out. 

Members have access to knowledge exchange, network events, research opportunities and engagement with like-minded cities around the world. They meet once a year at the Fab City Summit, where new cities also join the Network.

Distributed Innovation Workshops are also organised, where participants learn about various areas of innovation and sustainability.