Undeterred by the credit crunch and softening of New York’s real estate market, the Alexico Group is unveiling plans today for its 57-story luxury condominium tower in TriBeCa, which is poised to alter the skyline of Lower Manhattan with its Rubik’s cube-like design.

Construction is well under way on the ambitious, $650 million tower that weds the work of a Pritzker Prize-winning architectural firm, Herzog & de Meuron, with globular steel sculpture on the ground floor by a Turner Prize-winning artist, Anish Kapoor.

“It is product-driven — if you have an extraordinary product the market doesn’t even matter,” the developer, Izak Senbahar, said in an interview.

The 145 apartments at 56 Leonard St., at the corner of Church Street, will run between 1,430 square feet and 6,380 square feet and cost $3.5 million to $33 million. Thus, even the lower-end condominiums are being offered at more than double the $1.3 million median sales price of downtown condominiums, according to a second-quarter market report from Prudential Douglas Elliman.

Eight penthouses will occupy full floors and two others will occupy half floors.

So far there have been double-digit sales, according to the developer.

Through the staggered progression of twisting floor plates, referred to by the developer as “houses stacked in the sky,” each of the apartments will offer private outdoor spaces and some of the most unobstructed views available in Lower Manhattan.

The building joins other high-profile residential projects in the area bucking the real estate downturn, including Larry Silverstein’s new tower at 99 Church St. and Forest City Ratner’s Beekman Tower at 8 Spruce St., designed by Frank Gehry.

Mr. Senbahar said he is seeking to draw an international clientele to the building and, by offering the Kapoor sculpture, aims to make the building a new cultural destination for TriBeCa and Lower Manhattan, which is in the midst of a construction boom.

The bottom half of the building was designed to “mesh with the fabric of TriBeCa,” according to Mr. Senbahar, while the design of the upper half of the 800-foot-tall tower borrows themes from the downtown and uptown skylines.

“As a developer you have two responsibilities: You have to be respectful to the fabric and the skyline of the city and contribute something to the city. Some developers don’t understand that when you build a building it stays there for a long time,” he said.

The architectural firm Herzog is behind Ian Schrager’s 40 Bond St. condominiums, the Tate Modern Museum of Art in London, and the Bird’s Nest stadium of the Beijing Olympic Games.

The Alexico Group acquired the site for the tower from New York Law School for a reported $140 million in 2006. The school sold the land, which was the site of the former Mendik Library, and is building a new nine-story library on an adjacent lot.

The tower is scheduled to open in 2010.