Barcelona City Council is driving the BUITS (Empty Urban Spaces with Territorial and Social Involvement) Plan to provide a temporary social and community use for some of the municipally owned land sites that are currently in disuse.
This "empty space" plan invites the city's public and private non-profit organisations to propose a use or activity of general interest and temporarily run a site. Their proposals will be assessed and selected by an evaluation committee which will give special consideration to the programme's flexibility, its short-term and provisional nature, efficient self-management that keeps the facilities in good condition, and any positive social impact on the city as a whole.
So, an essential feature of the plan is the involvement of civil society in defining, installing and managing urban spaces.
You can find information on the project and its implementation on the BUITS Plan website.