The New York City Landmarks Preservation Commission focused on rooftops yesterday.

It declared Paul Rudolph's famous and controversial penthouse atop a 1860 townhouse at 23 Beekman Place a landmark.

It approved a spectacular two-story high honeycomb skylight roof-top addition designed by Morris Adjmi at 33 West 19th Street in Chelsea, shown at the right.

And it approved a revised designed for the roof of the Greenwich Hotel, developed by Robert De Niro in TriBeCa.

The three-story Rudolph penthouse extends considerably out over Beekman Place as well as the rear of the building. It was created by the famous architect as his home in 1961.

"The juxtaposition of modern and traditional forms creates a dialogue between the old and the new, and makes this building one of the most provocative landmarks in

New York City," said Chairman Robert Tierney. "The Rudolph penthouse also is the City's only landmark whose significance stems from a 1970s intervention."

Rudolph was the chairman of the architecture department at Yale University from 1958 to 1965, and designed the Art and Architecture Building, now known as Paul Rudolph Hall. He studied under Walter Gropius and Marcel Breuer at Harvard University's Graduate School of Design, and designed an unrealized plan for the Lower Manhattan Expressway. He executed five projects elsewhere in the City, including two townhouses in Manhattan and Tracy Towers, Davidson Houses and Middletown Plaza in the Bronx.

Katharine Cornell, a renowned stage actress, and her husband, producer-director Guthrie McClintic, bought the townhouse in 1922 and lived there until 1951. The couple collaborated on 28 theatrical productions.

The townhouse was originally constructed in the 1860s, and re-built in 1929 with a Neo-Classical style facade. The base has three round-arched openings, a wood-paneled door with an arched transom that features scalloped details, and a continuous flat metal awning between the ground floor and first story that's supported by four metal columns.

The penthouse begins at the fifth floor and is constructed with exposed painted steel I-beams and metal panels that frame the face of the structure.

An earlier plan by Mr. Adjmi to add several floors to the through-block building at 33 West 19th Street was rejected as too tall by the commission a couple of years ago. His new plan adds only two stories.

The very dramatic skylight consists of two "peaks" tilted and setback from the building's large cornice. The building originally was erected in 1903 as a 6-story structure designed by H. Waring Howard.

When it was rejected by the commission in July 2009, the Historic Districts Council objected to Adjmi's proposed addition of several stories to the building:

"HDC is troubled by the continuing trend of looking at our city's smaller structures as bases for larger ones, of preying on them rather than appreciating them for what they are. Approving this application would make a mockery of the Commission's decades of work to keep rooftop additions minimally visible and would signal to other developers that the sky's limit even in historic districts."

Today was also the first day on the Commission for architect Michael Goldblum, who replaces Stephen F. Byrns, also an architect, as the Bronx representative on the panel. Byrns stepped down from the Commission last year after more than six years of service. Commissioner Goldblum is a graduate of Columbia College, and received a Master of Architecture degree from the Columbia Graduate School of Architecture and Planning in 1984.

In other business, the Commission voted to hold public hearings on proposals to protect a total of approximately 790 buildings off of West End Avenue on the Upper West Side of Manhattan through the expansions of the West End Collegiate and Riverside West End Avenue historic districts. The Commission also held a public hearing on a proposal to give landmark status to the Engineers Club building at 32-34 West 40th Street.