Steve Hafner, who co-founded travel site Kayak, and is the company’s CEO, sold his 4,871 sq. ft. condo in the Chelsea neighborhood of Manhattan. The residence changed hands for $23.5 million, reflecting a loss of half a million.

The property is located in Walker Tower, a 1929-built building that was, in a former life, the New York Telephone call center; it was converted and opened about a decade ago.

Hafner’s unit is a duplex. It features two suites on the second floor and the master, which features corner glass and a marble-clad bath with a cast iron rub, on the first. Like all units in the building, it begins with a formal and very large foyer.

In the shared living spaces, espresso-colored oak floors in a chevron pattern and steel-framed windows and doors are highlights, with plank used for the bedrooms. Other details include custom millwork, radiant floors in the master bath, and 14-foot ceilings. Specialized rooms in the common area include a library.

The property’s outdoor living space is divided into two large terraces. Views take in Manhattan and the Hudson.

Hafner previously co-founded Orbitz.