This is probably old news, not found it on DC anywhere, though, so here goes...
Ever wanted to walk around a real life version of Half Life 2, complete with ledges that will easily send you to your grave? Well, now you can. Simply visit the Caminito del Rey http://en.wikipedia....iki/Caminito_del_Rey
and start having instant Half Life flashbacks.
Here's a youtube clip (one of many) which resembles the best complete "walkthrough" of the level.
For added authenticity, take your own headless, plucked, chickens and pretend they are Half Life Headcrabs.
(Looks like it's going to be a tourist destination eventually as there are plans to reopen the path - at the moment you have to abseil to it.)