Asahi is is one Japan's largest beer companies. The headquarters features two buildings -- the golden, taller one, meant to evoke a tall glass of beer, and the smaller, more architecturally striking one that people around the world recognize.
That thing on top is officially called the "Flaming Ornament," but it is known by many other names as well. Some refer to it as a parsnip, others by its nickname, "The Golden Turd." It's certainly an odd element to see.
The tour guide suggested it lays on its side due to a design error. It was intended to stand up on its bulbous end and really call to mind the the brewery's Dynamic Heart. The flame turned out to be too heavy, though, and the in the end they had to lay it down. (I've haven't confirmed that part of the story, but it seems plausible).