The top floors of the 16-story Mark Hotel at 25 East 77th Street are being converted to residential condominiums by the Alexico Group of which Izak Senhabar and Simon Elias are principals.

The lower floors will remain as a hotel and the building will be known as The Mark.

Jacques Grange is designing the interiors of the hotel and most of the apartments and SLCE is the architectural firm for the conversion.

The building will have a 24-hour concierge and doorman, a fitness center, a business center, multilingual secretarial support, valet parking, limousine service. In addition, Frederic Fekkai will operate a Salon Mark and residents will have signing privileges at Salon Mark and Bar Mark in the building and Sant Ambroeus, an Italian restaurant a few doors up from the building on Madison Avenue revered for its cappuccino.

The project, which is expected to be completed next summer, will have 49 apartments ranging in size from a 481-square-foot studio on the 9th floor that has an estimated price of $1,925,000 to a 858-square-, one-bedroom with a bath and a powder room on the 9th floor that has an estimated price of $3,350,000 to a 1,544-square-foot, two-bedroom with two baths and a powder room on the 9th floor that has an estimated price of $6,250,000.

A 2,233-square-foot, three-bedroom, three bath and a powder room unit on the 9th floor has an estimated price of $8,450,000. A 3,183-square-foot, three-bedroom, three bath and a powder room unit on the 15th floor has an estimated price of $15,750,000. A 3,789-square-foot, four-bedroom, four bath and a powder room unit on the 14th floor has an estimated price of $18,750,000. A 4,788-square-foot, five-bedroom, five bath and a powder room unit on the 14th floor has an estimated price of $23,500,000.

The 9,799-square-foot, five-bedroom seven bath and two powder rooms penthouse has an estimated price of $56,000,000.

The beige-brick building, which was erected in 1927 and designed by Schwartz & Gross, has one of the city's most distinctive roofs, a copper-clad sloped pyramid cut off at the tope. The building is directly north of the Carlyle Galleries Building at 980 Madison Avenue where Aby Rosen, the owner of the Seagram Building and Lever House, was unable to get a certificate of appropriateness from the Landmarks Preservation Commission for a design he commissioned from Sir Norman Foster for a silvery glass cylindrical tower roof addition placed at the northern end of the building right across from the entrance to The Mark.

For several years, the Mark Hotel's lobby was decorated with superb paintings by William Holbrook Beard, a 19th Century American artist noted for his amusing paintings of animals involved with human activities. Those paintings were recently put up for auction.

Several of the apartments will have wall-mounted panels for control of temperature and motorized blackout and decorative shades and Miele Touchtronic Series washers and dryers.

Kitchens will have Boffi high-gloss white lacquer upper cabinetry and brushed aluminum lower cabinets, black granite countertops, Gaggenau ovens and electric cooktops, Miele dishwashers and SubZero refrigerators.

Bathrooms will have marble flooring and walls and Kohler Tea-for-Two soaking tubs, heated tower bars, and Duravit wall-mounted Happy D. water closets.

The penthouse will have fireplaces, a "personal two-story lift," a skylit conservatory, a living room with a 26-foot-high ceiling, and a 2,300-square-foot terrace.

Alexico acquired the leasehold interest in the building for about $150 million from Mandarin Oriental Management. The hotel, which then had 119 rooms and 57 suites, is cattycorner to the Carlyle Hotel and until recently Issey Miyake occupied its Madison Avenue corner store at 77th Street.

The building has a three-story, rusticated limestone base, a large entrance marquee on 77th Street, balconies on the 14th floor and arched windows on the 15th floor.