10. 550 Madison Avenue, Sony Tower $1.1 Billion

550 Madison Avenue with its “Chippendale” cutout on top

The Sony Tower was built by architect Philip Johnson and John Burgee and is notable for its “Chippendale” cutout roof. At the bottom, there is a privately owned public space and a SONY technology lab. In 2013, the building was sold to the Chetrit Group for $1.1 billion, a price Bloomberg Technology called “aggressive.” The Sony headquarters were to stay in the building until 2016, whereupon it will move to 11 Madison Avenue (also on this list). The top floors were to be converted into luxury condos designed by Robert A.M. Stern but as with a forthcoming sale of the building for $1.3 – $1.4 billion, it looks like the condo plans will be dropped.