One of the reasons to love Manhattan is clearly Central Park. New York Magazine asked us to venture a wild guess as to what Central Park was worth in the article Reasons to Love New York: Because We Wouldn’t Trade a Patch of Grass for $528,783,552,000. 
So there is no confusion, this is a purely hypothetical, far-fetched, non-scientific wild guess based on so many caveats (and done in about 3 minutes) that reality doesn’t enter into the equation so we are not violating any licensing requirements…got it?
After the dust settled, here’s the math used.
Webmaster’s Note: Its quite possible, and highly likely, that the net value of all of Manhattan would be less after Central Park was developed. A very high level of inventory that might take decades to absorb would be created, but assuming instant absorption, units facing the park would lose their views, proximity to the park would not matter anymore and a cultural and recreational resource would be lost to all homes in Manhattan. In other words, it would likely be bleak on the real estate front.