35 East 68th Street

35 East 68th Street, located between Park and Madison Avenues on the Upper East Side, is one of those buildings that is not to be messed with. It's a 13,000-square-foot Beaux Arts mansion designed as a private residence for Harvard-trained physician Dr. Edward Kellogg and grain fortune heiress Mary Dows by Carrere & Hastings–the same architecture firm behind the New York Public Library. Since the now-landmarked building was completed in 1901, it has maintained its elegant, carved limestone facade. The interior, however, is a different story. Somewhere along the line the mansion was converted into a co-op apartment building, split into eight units. Seven of the eight co-ops were on the market this February for $34 million, but it looks like a sale never happened. Now this three-bedroom duplex is up for sale on its own.
See the interior