Jesse,
It's actually two words WOLF TRAP and it is a national park.
Wolf Trap holds the distinction of being America's only National Park dedicated to the performing arts !! (their words, not mine)
There is more than one venue but The Filene Center is the one that Gord and most musical acts play in.
It's pretty standard inside and the seats and configuration are just like any medium sized playhouse. It's nice because it's open to the air unless it's too hot but most night's it's lovely. The hill is sloped just right so that the party people/lawn sitters have a good shot at the show.
Check the link and look at the lineup - it's the same people that show up at Massey and all the other artsy places that Gord plays now at this stage of his career. It's like they follow one another around the US and Canada.
Plus it is a very beautiful park by itself. Come down some time and I'll show you and yours around.
http://www.wolf-trap.org/
Bill