What is Musso's?

Hank and Sarah often retreat to this popular restaurant/ bar when life gets too overwhelming. It's also, according to narration, a popular place for the citizens, celebrities and deal makers of Hollywood to see and be seen. At one point, Hank comments in narration that in his earlier, harder-drinking days, that's exactly the sort of thing he would come to Musso's to do, but that now, as both he and his life