The James Webb Space Telescope is being prepared for launch. Currently it is in a semi-deployed state (sunshields deployed, mirror segments unfolded) in a high bay. There has been a steady stream of employees and guests (any employee can bring in US person guests without any paperwork and foreign persons through the badging office).
It is a magnificent sight, a spacecraft the size of a tennis court (sunshields) and about two stories high. They are now integrating it into its fully folded launch configuration, so the current visitors will be the last human eyes that will see the on-orbit view of the spacecraft (it will be about a million miles out, so even the best telescopes aren’t going to be able to provide any details).
The viewing room is above the high bay and everyone has to have an employee escort. No pictures allowed. Not much in the way of technical data can be gotten. And it is a NASA bird- they have many more technical details on their website than can be gotten from the viewing (including high res photos).