If we had a nickel for every time we said to ourselves, "We wish our apartment was topped with a golden octagonal cupola so our dinner guests could easily locate it," well, we'd almost have enough money for the down-payment on this lower-Fifth Ave. penthouse. The asking of $17.9 million includes 80 feet of "greenhouse style windows," a "sybaritic" bathroom, and "a circular baronial limestone staircase." (Looks like Elliman's got new thesauruses!) The landmark dome on top is just gravy.
· Listing: 170 Fifth Avenue [Elliman]