As great as Overwatch may be, it's nature as a game-as-service title means that it's unlikely to support mods and user-made maps any time in the immediate future (although Blizzard's Starcraft 2 modding scene suggests that may change). If it did, we would absolutely want to play Joshua Llorente's stunning Cairo map, a detailed fly-through of which you can see within, as well as some high-res screenshots here.
Until Blizzard snap up this talented mapper, we can't run around Cairo, yelling at our friends for not standing on the capture points. Until then, bone up on what is available with out handy Overwatch map guide.
Honestly, if it weren't for the fact that it's clearly labelled as a fan-work, I could easily believe that this was an official Blizzard-made Overwatch map. The mixture of historical cliche and utopian futurist architecture is present and correct, as are the sweeping, slightly too cartoonish curves of many structures.
It's not just the map geometry that's stand-out stunning, but the texture work, too. Everything is in perfect keeping with the Overwatch aesthetic, and nothing is too sharp or obviously 'HD' enough to stand out (as it should be, ideally), but there are enough fine details (like the illuminated or reflective hieroglyphics) that it's hard not to be impressed.
It captures the 'softness' of Overwatch's world perfectly, perhaps even going beyond Blizzard's own best with details like light-haze visible over the most densely populated parts of the map. Fortunately, we're not the only ones to be impressed; Overwatch director Jeff Kaplan commented on Reddit that he'll be in touch with the map's creator.
This is also far from Llorente's first Overwatch-inspired map, and he's flexible enough to produce similarly gorgeous work in Unity 5 as well. You can see his fully gallery of work here - it all adds up a one hell of a resume, and I can only hope that Blizzard snap him up before another studio poaches such an obviously talented mapper.