"*As I said, it feels quite odd, and now even more so. Though I will now need to begin filling in the room, as I did not decide to maintain the same mass.*"
By now, I believe it's safe to assume the convoy has reached the city centre, wherever that is.
Well,
this is possibly a great opportunity the convoy would see the city center as it has been for a while. That's to say, I believe two skyscrapers were destroyed, give or take one, as I know at least one is gone, but I'm less sure if there were more.
The city center would also still be surrounded by a metal fence, and the roads blocked by Jersey barriers. The barriers are able to be moved, due to both being temporary and the requirement of moving vehicles in and out, though they are still concrete Jersey barriers. And a bit in front of the Jersey barriers are also a few wooden A-frame barriers, but they're just, well, wooden A-frame barriers.
There also wouldn't be much in terms of fortifications, or easily defendable positions, as the several roads mean that despite being choke points, there are several angles of attack.
And then for the primary feature that was added after Swaasnia took the city. A massive hole in the ground that is perfectly cylindrical, with a diametre that I don't think was specified earlier so I'm going to say that it is 35m, and that is in addition to the 20m diameter shaft that was built not too far from the hole, though the shaft actually has a fence around it, an elevator, and so other things. There are also the ruins of some construction equipment and vehicles that seem to have gone through something.