I love how organic all of this looks, like it grew and was built upon over time.
Do you have plans to expand upon this original build further? Do the pieces allow you to rearrange or do they only go together in one manner?
No plans right now, but it shouldn't be hard to do. I'm thinking about building up a moonscape so that the adventure can bleed outside of the terrain, but that needs some thought. One of the great things about this setup is how portable it is. You can fit all four pieces into a small carrying case (pic related). A third container would let me either add two more tiles or a drop cloth and exterior scatter terrain. Not sure if the handle can take that much weight, though. So that's an option for later. Of course, I could always just drop the whole thing on a ground cloth and do that without dedicated terrain, too. That's always an option.

You can rearrange them a little bit. The entry plaza and the parking bay can be swapped out for a second set-up, but that's it. It does change some of the tile connectivity, too. Until I play, I won't know for sure how big of a difference that switch makes.
I tried a lot of different geometries to give more options, but all of the ways to combine tiles meant too great a sacrifice in the... I don't know the word - the kayfabe? Believability? To make everything link together without a bunch of deadends or doors to nowhere, you need so many extra doors that it stops looking like an organic building and more like a paintball field, if that makes sense.