First, it’s huge. And it’s a treehouse! Many wondered how the heck we’d fit seven humans on this little lot. Even I was an early skeptic. The house officially clocks in with an interior width of 14 feet 11 ½ inches, yet there’s not a wasted fraction. From a bird’s-eye view, 3607 looks as if we dropped a long, skinny rectangle, Tetris-style, between its neighbors and the lush canopy.