Gartner Penthouse

Former technology executive Gideon Gartner is ready to unload his five-bedroom penthouse on the Upper West Side for $29.5 million. The lavish apartment combines three units and offers panoramic views of New York City.

The entrepreneur, who shares the home with his wife, Sarah, purchased the first set of condos in the Millennium Tower building at 101 West 67th St. in 2005 for $7.9 million, according to property records.

“They opened the door for us and my jaw dropped,” said Mr. Gartner of the striking views and expansive living room in the original unit. “We made an offer on the spot.”

The third condo was purchased in 2006 for $1.3 million. Combined, the penthouse measures nearly 6,000 square feet.

Most of the costly finishes were in place when Mr. Gartner bought the property, including the Hebron marble used throughout the condo and the striped ironwood and maple floors in the living room. The most significant changes were done to the third unit, which was transformed into a large office space.

Using switches from his desk, Mr. Gartner can lock the office doors, warm the floor under his toes and change a glass door from transparent to opaque when he wants privacy. “It’s very nifty,” he said.

Mr. Gartner spends most of his time in the office, but he says one of his favorite rooms is the library, which is outfitted with leather floors and kewazinga wood sourced from a tree in Africa. The wood was specially chosen, purchased and shipped to the city for the room.

The home, which has eight bathrooms and two kitchens, is full of contemporary furnishings. For large gatherings, Mr. Gartner uses the living room, which holds a Bösendorfer grand piano.

Mr. Gartner founded three information technology advisory firms, including Gartner Inc. in 1979.

Part of the reason he has decided to sell the property is because it is

a little too much. A good part of the apartment is not even used,

he said. The couple also plan to spend more time at their home in Aspen, Colo., and eventually to purchase another property on the Upper West Side.

The home was initially listed for $34.5 million in September, but the price was reduced by 14.5% in December, according to StreetEasy. Prudential Douglas Elliman Real Estate holds the listing.