After 9-11 our company got a job setting targets on the Capitol building so it could be laser scanned for a record. I wasn't on that project, but I don't think clearances were too bad. NSA/Ft Meade, you had to stop and get your vehicle checked. It was always amusing seeing the guys who thought a morning joint was a good idea being cuffed on the curb. Dumbasses...
On that job, I was out on the highway in front, and a helicopter came overhead, and told me we had to break setup. GWB was coming for a visit :^D