For security reasons, the Central Intelligence Agency does not give tours to
walk-in-visitors. It has, on rare occasions, granted limited campus access
to groups associated with the intelligence community. I've been on it.
They didn't give us a "pentagon-like" tour and show us the seal on the old
main lobby floor, or Nathan Hale's statute, etc., but keep us penned into
the bubble with copious amounts of security officers watching over our
group. But we did get to go to the gift shop and purchase CIA trinkets for
the grandkids!
The NSA does not give tours either. But they do have an "intelligence
museum" outside the main entrance.