Let's see. Not counting stores/conventions, just actual campaigns.
Played D&D in a basement in:
-- New York State (outer suburbs/Hudson Valley region)
-- Washington State
Played D&D above ground in:
-- New York State (living rooms & dining rooms, outdoors on the porch)
-- New Jersey (living rooms & kitchens)
-- Vermont (house)
-- Massachusetts (dorm rooms, shared dorm living rooms)
-- Washington State (dining room, living room, D&D "library" room)
But the coolest place? UNDER a dorm at college. We found a short wooden access panel in the wall of an early 19th century dorm, with wooden set of stairs behind it. It led to a dirt floored, stone-walled subbasement, with too-short to explore through tunnels running off it. Rumors (OK we created the rumors) had it that the room had something to do with the Underground Railroad, or forbidden frats (banned from our college in 1962, 30 years before us). Sitting down there playing D&D by candle light? Definitely something a Chick Tract or Tom Hanks movie would warn you against!
Eventually, Buildings & Grounds must have figured out they had a kid infestation, and sealed off the access panel. With us still inside!
OK, I made the last part up.
