Horizen Global, which is headed by Michael Yanko, has switched its plans for two West Side developments from residential condominiums to hotels.

According to its website, its plans for a 21-story residential condominium building at 39 West 23rd Street with 71 apartments now call for a hotel with 170 rooms and suites.

The Department of Buildings issued a building permit for the project last week and its design by Carlos Zapata Studio and Gruzen Samton LLP had been approved by the Landmarks Preservation Commission that requested the design be modified by reducing its height and it required the developer to restore and retain the facades of the existing low-rise residential building at 37 West 23rd Street.

The flamboyant and bold design calls for a white-glass-clad narrow tower that not only slants to the north above its-low rise base on 23rd Street, but also cantilevers over its rear yard and also slightly over an adjoining low-rise residential building that is part of its zoning lot to the east at 37 West 23rd Street.

The "whittled" design is not simple and there are a variety of other facets, and a few notches, to its facades.

The site runs through to 24th Street where a three-and-a-half-story, single-family townhouse would be erected as part of the development.

The project's chamfered design also is somewhat similar in concept to One Bryant Park, the much larger skyscraper being erected now on the northwest corner of 42nd Street and the Avenue of the Americas.

Mr. Zapata's and Mr. Samton's design, however, follows the strange logic of the city's zoning and building regulations and, as a result, represents an extremely intriguing and formidably sculptural form, especially for New York above the clean-cut lines of its low-rise base.

The tower of the mid-block building would be quite narrow with only about 3,500 square feet on a floor. It would be a few stories higher than the tall buildings at either end of the block but its slanted design would more views of the Metropolitan Life clocktower building on Madison Avenue as seen from the Avenue of the Americas than a sheer tower, Mr. Zapata said.

The top of the low-rise base on 23rd Streets projects out about 22 inches to "look like a cornice," he said.

The company's website now refers to the Horizen Tower as a "five-star boutique hotel" that "will have 170 rooms and suites, including a penthouse suite with a private garden, a 100-sear restaurant and bar, an additional patio bar, a screening room, banquet space, and a Jacuzzi bar."

The building would replace a 96-car parking lot.

Horizen Global's other Manhattan projects include Hudson Blue at 423 West Street and the Vu Hotel at 653 11th Avenue for the Kimpton Hotel and Restaurant Group of San Francisco.

In July, 2005, Horizen Global of its plans to convert the 14-story industrial building at 653 11th Avenue at 48th Street to condominium and rental apartments.

Mr. Zapata is also the architect for this project where the developer plans to cut away a "notch" in the southwest corner of the building and add that "space" on top of the building. The "transfer" will add about three floors to the building but not significantly change its total space. Mr. Zapata said that the plans call for preserving, cleaning and restoring the existing facade. "We want to respect the strength it has," he said, adding that the plans call for new multi-pane windows.

The building's new top would be setback and dramatically curved with a glass, or glass-and-metal facade. A curve will also be introduced in the "notch" where one side will be curved downward.

The building called for about 86 luxury condo apartments and 9 "affordable housing" rental units that would be located on floors 2 through 6.

A few months ago, however, Horizen Global changed its plans for the 11th Avenue property that will now be converted into a 222-room hotel with interiors designed by the Rockwell Group.