This 41-story, twin-towered residential condominium development at 80 Riverside Boulevard occupies the blockfront between 64th and 63rd Streets.

It is across 64th Street from The Avery, a 30-story condominium development and both are projects of the Extell Development Corporation on land it acquired from Donald Trump, who has developed several residential towers just to the north.

The Rushmore has been designed by Costas Kondylis and Partners, the architectural firm that has also designed the Avery and many of Mr. Trump's projects.

The Rushmore has a 16-story base with corner windows at the north and south and a setback at the 4th floor in the center of the blockfront. The twin towers are setback and are joined at the lower three floors. They are illuminated at night.

Mr. Kondylis has borrowed a stylistic treatment of the towers from Cesar Pelli's World Financial Center at Battery Park City where the upper part of the towers have slightly protruding sections with different fenestration patterns.

Mr. Kondylis has kept his towers symmetrical and the protruding sections stop at the 34th story and the top five floors have a banded fenestration pattern reflecting the fact that are "penthouse" units.

The floor plan of the full-floor Penthouse A indicated that the apartment has an entrance gallery that leads to a very large living and dining room space with a fireplace and also has four bedrooms and a large family room and kitchen area facing the Hudson River.

The 425-foot-high Rushmore has 289 one- to five-bedroom apartments and was completed in 2008.

The building has 6 duplex apartments entered on the ground floor. Floors 2 and 3 have 22 apartments. Floors 4, 5 and 6 have 18 apartments. Floors 7 through 14 have 10 apartments. Floors 15 through 17 have 6 apartments. Floors 18 through 36 in each tower have 2 apartments. Floors 37 through 41 in each tower have one apartment.

The building has a swimming pool, La Palestrina Fitness and Wellness Services, a 185-car garage, a children s playroom designed by Kidville, NY, a billiards room, Abigail Michaels concierge, a bicycle room, and a theater and entertainment suite.

Residents were offered a choice of three kitchen designs with fixtures by Sub-Zero, Viking, Miele and bathrooms have fixtures by Kohler and Waterworks.