How fast would you have to cycle a bike to power a lightbulb? What about making a cup of coffee? One of the things that makes it hard to save energy is that for most of us the ways that we use and lose energy seem fairly abstract.
From fortresses that rise like a phoenix from the ashes, to walls that whisper secrets of the past - this isn't a new Harry Potter novel, it's a collection of best practices on cultural heritage in the EU's cities and regions.
50 cities have now adopted the Eurocities Declaration on citizens' engagement, demonstrating their commitment to create a Europe where people come first and citizens have a role in new forms of participatory democracy.