While they might look simple on the outset, there is a ton of work that goes into the creation of FPS maps, especially for those that are going to be used for competitive play. As such, it shouldn't come as much of a surprise to hear that Overwatch's Watchpoint Gibraltar map underwent an absolute ton of changes before finally becoming the map we know and (sometimes) love today.
If you're wondering what that journey was like, as well as what some of the earliest versions of the map looked like, allow me to share with you the recently posted behind-the scenes video. It's fairly short, totaling at around 2 minutes, so I would definitely recommend you give it a look if you're even remotely interested in game design. Here's the video:
Additionally, Overwatch's Principal Level Designer David M. Adams mentioned on Twitter that the team created similar videos for a couple of the other maps, and that he is looking into posting them as well. Whether he'll actually manage to find them given that they're fairly old, I'm afraid only time will tell, but I really do hope he does because I do love the occasional peek behind the curtain!
And finally, if you're as interested as I am in behind-the-scenes videos, you might also want to check out some extremely early Overwatch test footage. It's quite a lengthy presentation, and it features a variety of heroes throughout their whole development process, so I would heartily recommend you give it a look. Enjoy!