A four-level "quadplex" penthouse located in the skinniest skyscraper on Manhattan 's Billionaires Row just hit the market ...

The four-story “quadplex” of Steinway Tower overlooks Central Park and offers 360-degree views of New York City.

The Big Apple just got bigger — at least when it comes to the price of this newly listed “quadplex” penthouse. On Thursday, ...

The mansion-size quadplex penthouse on the 80th through 83rd floors has multiple terraces and views across the city ...