They blew up their original headquarters (possibly another one as well), and then they were in the hotel seasons 2-4. Season 5 was just the season that shifted them from a detective-esque show to one about them running a super-powerful law firm. And it opened them up to a series of supremely surreal concepts that made…

I think the only other show that's done what Archer just did is Angel which, also in its fifth season, found a new premise while keeping the same characters and thus reached a new creative height.