Kingdom Come by Alex Ross and Mark Waid

The more official write-up is below, but I just wanna say that this is one of the most beautiful and thought-provoking stories I've ever encountered in any medium. If you haven't read it, please give it a go. You won't regret it. Now, the blurb:

In the near-future world of Kingdom Come, superheroes are ubiquitous, but heroism is rare. After decades as Earth's champions, the members of the Justice League have all retreated out of the public eye, replaced with a new generation of crime-fighters whose brand of justice leaves humanity terrified, rather than inspired. But with the planet's future in jeopardy, Superman, Wonder Woman and Batman must come out of retirement to make one last stand for truth and justice...

From comics writer Mark Waid and artist Alex Ross comes this definitive collection of the seminal masterpiece Kingdom Come, with more than 100 pages of sketches, annotations and other behind-the-scenes features.