I keep trying to get a definitive answer on the real-world location of the BAU offices, but the website is darned fuzzy. Much complicated by the BAU having once been the BSU, before the BSU divided into the two more specialized units. The BSU is definitely part of the Quantico complex, though. (And Mulder, we learned from various X-Files references, was a BSU agent, back before the units did their cell-mitosis trick.)

[Dear heaven, woman, quit exposing your TV geekitude.]

Aw, heck, I should just phone the public info officer in the local field office and ask. But that would take the mystery out of it...