X-Men: Days Of Future Past - 31 Rare Images You Must See

It was the directorial return of Bryan Singer to the X-Men franchise after 11 years away, after the filmmaker had kickstarted the (still running) superhero movie revolution and left the X-Men films with the high watermark of X2 in 2003. Would Days Of Future Past, joining the cast of Singer's originals up with Matthew Vaughn's younger First Class crew, be a success? Of course it would - Days Of Future Past brought Singer back onto home turf to make the biggest and quite possibly best X-Men movie yet, a nearly $750 million-grossing behemoth that got fans clamouring for more. Behind the scenes, though, Days Of Future Past had been a predictably huge effort. For one, the film would take place across three different timelines: 2023, 1973 and the present day. This would require Singer and screenwriter Simon Kinberg to assemble the largest X-cast of them all, bringing in stars of future (Ian McKellen, Patrick Stewart, Halle Berry) and past (James McAvoy, Michael Fassbender, Jennifer Lawrence), introducing newcomers (Peter Dinklage and Evan Peters) and using old-reliable Hugh Jackman to join everything together. The action would take place across the globe, involve hundreds of cast and crew filming for five solid months and, in total, cost 20th Century Fox $200 million to finance. In the end, it would be worth the effort, but a glimpse behind the scenes gives an idea of what a massive undertaking it was.

Singer makes good on his bet to get an X-Men 'X' tattoo if Days Of Future Past grossed over $700 million at the box office. Patrick Stewart, top left, watches on in fascination.