In the announcement of 343 Industries' next big game in the Halo universe "Halo 5: Guardians" they posted a piece of concept art on their site, Halo Waypoint, have a look below.
So, if you look at the image the main focus of this piece of art is of a group of buildings of some kind of facility, the buildings appear to have been built in a canyon within and around rocky cliffs that seem to be located in a desert landscape, possibly the same world that Master Chief was on in the 2013 E3 trailer, we can also see a person or a humanoid being walking through the grounds of the buildings.
The architecture of the buildings themselves don't seem to be very Human or Forerunner like, so it leaves the question of who built them and what is the purpose of this facility? If you look at the huge rock pillar there seems to be (I could be wrong) a giant sitting or standing against it holding and looking at an object, a weapon perhaps? could that thing be a Guardian if it is in fact a living being or an AI? Is it just a statue?
In the sky there are what appears to be tentacled creatures (or some kind of odd ships?) flying over the cliffs that may leave a burning question to many of what they are. Also in the sky there are two suns that are bearing down on to the world, where this place is a mystery at this point until we get more information further down the road.
So what do you think of this piece of art, where do you think it is set?
Source: Halo Waypoint