Satellite shows what's happening in the East Wing of the White House (arstechnica.com)

a ball room would be an interesting cover for bunker hardening.

a non critical void space, provides a red herring for penetrating munitions, before they hit actual bunker structure.

germany was doing this with uboat gantries, and munitions factories back in the 40's

He's not demolishing and reconstructing just to leave after 3 years. Saying this as an immigrant who lived under full on military, and pseudo-autocratic democratic rulers.