Marketing has started for the 20-story residential condominium building at 535 West End Avenue on the southwest corner at 86th Street.

Demolition started last fall.

IMICO West End LLC., of which David Rothstein is an executive vice president, is the developer. It is a project of Extell Development.

When demolition started last fall, the building was planned to have 34 apartments and, according to an offering plan filed in July for testing purposes with the New York State Attorney General's Office, the project would have a purchase price offering of $274,105,000.

That plan said there would be four studio units of 615 to 725 square feet on the second floor, larger units above the second floor and "penthouse" units on floors 16 through 21 which would seven-bedroom units with seven-and-a-half baths with 6,275 square feet priced at $11,600,000 to $12,100,000.

An ad that appeared in yesterday's edition of The New York Times Magazine, however, describing the project as "The Finest Pre-War Ever Built," said it was "a limited edition of 22 exquisite half and full floor condominium residences."

The ad showed the rendering at the right and a floor plan of a full-floor, 7-bedroom, 7.5-bathroom unit with 8,451 square feet that was notable for have a library at the curved corner at 86th Street that was to the east of a living room smaller than the dining room.

The building will have a landscaped courtyard, a recreation room a fitness center with a swimming pool, and a game room.

The red-brick building will have a swimming pool, a La Palestra fitness center, a private courtyard, a private lounge and club room and kitchens by Smallbone of Devizes.

The building will have a three-story rusticated limestone base and the top floor will also have a limestone facade. The building will have a canopied entrance beneath an arched window on West End Avenue and some arched windows on the 2nd and 14th floors and all the windows on the 20th floor will be arched. There is a setback at the 15th floor.

Lucien Lagrange, who has designed many high-rise luxury apartment towers in Chicago, is the architect for the project.