[Not spoilers for the show, but possible spoilers for the Art Book ahead]



What is this?

It can’t be the Lunar Sea Spire:

It also can’t be the Communications Hub:

It is currently the only diagram from It Could’ve Been Great that hasn’t been seen in the show, or even hinted at.

So where is it?

From what we can tell, it is surrounded by mountains, possibly placing it in a valley somewhere.

This diagram shows us all the structures that were “originally built on Earth” by Homeworld.

Some of these locations have been semi-officially confirmed (sort of) by the art book:

Ignoring some oddities due to this likely being concept art rather than a finalized, 100% canon map (like the spot where Ocean Gem took place being marked on the Moon Base computer for some reason), it does narrow us down to a location: South America (or Pangea as it’s apparently called in SU).

You see, every location on the show, regardless of whether or not it’s position makes sense, is marked on this map, and the dots on this map all match up with dots of the Moon Base map (regardless of whether or not it makes sense, again).

The only one NOT on the art book map is the dot in South America. Now, you may think that’s Centipeetle’s ship, but that’s much north, as shown in Friend Ship:

And, going by both the Art Book and the Moon Base Map, the South America Dot is located right between two mountain ranges (they’re far apart, yes, but the other diagrams simplified and squished down their respective locations)

So what is it?

Since it’s relatively close to Centi’s ship, my guess is that it’s some sort of landing complex for incoming and outgoing ships, with the spire being essentially like an air traffic control tower and the two diamond-shaped things next to it being landing beacons.

Or maybe I’m dead wrong lol