Here’s a somewhat more zoomed in view of that location in Google Maps. I wonder if SpaceX has purchased/leaded that entire area? I would guess so. They are going to need a lot of space. This is exciting!
Looking at the greyed area in my map and compare it to your close up map, you can see there is a fence along the upper section. It runs just below the building with the hole in the roof. If I am correct then the space has 12 individual buildings, three cranes, and a big pile of dirt on it. Three of buildings are directly connected to another building. You can tell by comparing the shadows in your two different pictures.
If I remember correctly, there are permits for "improvements" to the property which means that SpaceX will be tearing down and adding things needed for their purposes.
Edit: If you go to a street viewing, the buildings that are there are really beat up and likely not too usable. Now that everyone is aware that SpaceX owns this property, I expect the company will come out of stealth mode and fix the place up quick. It's a big property with some big buildings on it.
The property includes a power substation...
2nd edit: Looking at the area on Google Maps, it's a really run down section of the terminal. It's placed very well near the entrance. SpaceX probably bought it for nothing and turning it into a major manufacturing facility will be an impressive feat.
Good article about this:
SpaceX BFR Construction Site Identified? – Chris Rogers – Medium