Imagine, if you will, a full vacant block fronting on Central Park and Broadway and 61st and 62nd Streets.

What to do?

Well, if you are a Donald Trump wannabe, you might want to erect a very tall, slim, glass tower like Trump World on First Avenue at 48th Street.

Or, if you are a David Childs/Daniel Libeskind-like architect you might build a cluster of angle-topped towers of different heights.

Or, if you admire the multi-towered "skyscraper palazzi" of Emery Roth along Central Park West, you might be a twin-towered skyscraper somewhat like the Time-Warner Center at Columbus Center, which is a block away from this site.

If you are Arthur W. and William Lie Zeckendorf, the co-chairmen of Zeckendorf Development, the builders of the former Mayflower Hotel site at 15 Central Park West, the site in question, you would hire Robert A. M. Stern and SLCE Architects to design a 19-story structure on Central Park West and a 35-story, mid-block tower behind it and separated by a 70-foot-wide private courtyard and put a low-rise retail component along the angled west end of the site along Broadway.

Robert A. M. Stern, who has designed high-rise apartment towers in the city such as the Chatham at 181 East 65th Street, TriBeCa Park at 400 Chambers Street in Battery Park City and the Westminster at 180 West 20th Street, is known as a post-modernist architect as well as one of the country's foremost architectural historians.

His design here almost reproduces the massing of the former Mayflower Hotel for the lower of the two buildings but instead of brown brick has clad it, and the higher tower, entirely in limestone and glass. The west end of the site has been vacant for 18 years and demolition of the Mayflower Hotel began several months ago.

The long-awaited design was published today in an article by David W. Dunlap in The New York Times. The article stated that the developers are now showing its plans for the $1 billion project to community leaders on the Upper West Side, adding that "Unless Zeckendorf Development applies for a permit for a parking garage, the project will be construction 'as-of-right' under existing zoning rules."

The lower tower will rise 231 feet on Central Park West while the mid-block tower will be 550 feet tall, or about 35 feet shorter than the Trump International Hotel and Tower across the street to the south and 210 feet taller than the Century Apartments across the street to the north.

The development will contain a total of 201 condominium apartments and is expected to be completed in 2007.

The taller of the two buildings has a slightly asymmetrical top. Both buildings are parallel to Central Park West, which means that the west-facing buildings of the lower building and the east-facing apartments in the lower half of the taller building face each other across the 70-foot-wide courtyard. If the taller building had been placed parallel to the cross-streets on the northern end of the block and the lower building had been placed near the west end more park views could have been achieved. That, and single-tower schemes, however, would most likely require special permits and/or zoning variances that most developers are eager to avoid.

The site was acquired last year from the Goulandris family by a joint venture of William Lie Zeckendorf and Arthur Zeckendorf, the Whitehall real estate fund of Goldman Sachs and an investment company controlled by Eyal Ofer for more than $400 million.