Nyapbp took a tour of DKE's HQ this year when she was in Ann Arbor for the Pi Phi chapter's centennial celebration. My chapter had a formal at the "Deke Shant" when I was an undergraduate, but this was before it became their HQ. It's a mysterious, old building with lots of symbolism.
Also, I haven't gone yet, but Sigma Nu's HQ is in the same town where my daughter goes to college, and I've been told we should visit. It's a beautiful antebellum mansion on a hill.
http://www.sigmanu.org/about/visiting_headquarters.php
I've toured our HQ. From our website, it appears anyone can take a tour. There is even a virtual slideshow on-line.
http://www.gammaphibeta.org/aboutus/...alheadquarters