Alpha Phi Omega was founded in Easton, PA (about a hour north of Philly, near the New Jersey border).
During our first 5 years, our 'National HQ' was were ever our National President (who was also our Founder) was. We literally had 4-5 different 'sites'.
When the second person to be our National President was elected, the National HQ moved to where he was, in Kansas City, MO. Its been there ever since (but in 2-3 different locations in the city), tho when we built our own building to house it in 1990, we moved to the nearby community of Independence, MO. The location is pretty good, being about in the middle of the country, also there are several other non-profits headquartered in the area. (Camp Fire USA springs to mind).