From the beginning of the last NYC condominium boom up to today, Manhattan condos have been locked in a strange and occasionally silly sort of arms race. It's not one that puts anybody's lives at risk, thankfully -- this sort of arms race pertains mainly to amenities, and which condominium can have the biggest and best extras to go along with those condos for sale. It makes a certain type of sense, given that there are only so many ways that one luxury condominium for sale can differ from another luxury condominium for sale. And so we get the spectacle of The Aldyn with its 40,000-square-foot fitness center and the Cipriani Club Residences' 20,000-volume library and 20 Pine's private subway entrance. These are all nice things to have in a condominium, of course, which is why the aforementioned rank among the most popular Manhattan condo listings at New Construction Manhattan. But the appeal of those elaborate amenities is a bit more abstract than the simple joys of one of Manhattan's rarest and most sought-after amenities -- a private terrace.