PNC Financial Services Group is aiming to build the largest environmentally friendly, mixed-use building in the United States with construction of its 23-story office tower on Fifth Avenue, Downtown.

In unveiling the latest renderings of the structure today, PNC officials said the building will be designed and constructed to meet Leadership in Energy and Environmental Design (LEED) standards established by the U.S. Green Building Council.

Work on the building is expected to start in August with the demolition of 13 PNC-owned properties on Fifth Avenue between Wood Street and Liberty Avenue. The new skyscraper will be the city's first in two decades.

The building will feature 11 stories of office space, nearly half of which will be occupied by the law firm of Reed Smith. PNC is expected to occupy the rest of the office space. There also will be a 10-story upscale hotel with 185 rooms and 30 luxury condominiums spread over the same 10 floors. While hotel guests and condo owners will share the same floors, they will be separated from one another. Rounding out the construction will be a 300-space parking garage underneath the building. There will be retail and restaurant space on the lower floors.

Gary Saulson, PNC director of corporate real estate, said the bank is negotiating with a hotel operator, one he would not name. He described it as a "well-known hotel flag."

The total cost of the project is expected to be in excess of the original $170 million price tag, largely because of the addition of about 35 hotel rooms. The building is being financed with the help of $48 million from public sources -- $30 million from the state and $18 million in tax increment financing. Construction is expected to be finished in late 2008.

More details in tomorrow's Pittsburgh Post-Gazette.