The four photos show progress being made on the foundation of the structure with some rebar and concrete work visible.
#applesnewhq... It does have a certain death star look to it.
More details coming out as progress continues at #applesnewhq Some rebar, some concrete work...
Apple's spaceship continues... I'll tweet some detailed pics of #applesnewhq
Digging continues on the tunnels. But might be a while before @tim_cook and co. move in.
AppleInsider notes that "it appears preparations are being made to pour the concrete foundation that will serve as a base for the three-story building. Of note is rebar work being done to retaining walls ringing the build's perimeter, which will likely be paired with a comprehensive drainage system to avoid water ingress and lower level flooding."
More details on the structure can be found in Apple's presentation video.