That is his secure conference room in Crawford.
Might be subterranean. In fact, that would make sense wouldn't it? He's got to have some sort of bunker there. (I hope)
It just never occurred to me till I saw that photo that he might have, and of course he'd need, a secure underground bunker facility in Crawford. Wouldn't want to put that in the basement of his house though. ;-)
It doesn't have to be subterranean. I've been in many secured rooms in my life. They can't have windows, and the walls have to be thick enough so that no one can eavesdrop through the electronics equipment. Controlled access, too, of course.
I wouldn't think they'd have a subterranean bunker there. After all, planes can't fly over, and no one can drive anywhere near it. He doesn't need the protection from harm, just protection from eavesdroppers.
I like it when he's at the ranch. That and Camp David are the safest places for him to be. Even more so than at the WH.
It looks like the insideof a trailer to me. Or mabe a double-wide.