Through good times and bad, PNC Financial Services Group has remained bullish about Downtown Pittsburgh.

Its headquarters tower, One PNC Plaza, has anchored the corner of Fifth and Wood since 1972. Two PNC Plaza, which it acquired in 1993, is a Liberty Avenue landmark. PNC Firstside Center opened in 2001 on a site near the Monongahela River that was once the location of a Baltimore & Ohio Railroad terminal. There the financial giant's white-collar employees provide back-office banking services -- one of the pillars of the 21st-century information economy -- in a place where railroad workers oversaw the physical transportation of goods and people, critical elements of 19th- and early 20th-century development.

PNC's announcement this week of a $170 million plan for Three PNC Plaza, proposed for a sad-looking stretch of Fifth Avenue, is welcome news for Downtown and for southwestern Pennsylvania. Three PNC Plaza would be the first skyscraper built in the city in almost 20 years. The project includes a hotel, condominiums, offices, a restaurant and stores. It will also feature the relocation of the Reed Smith law firm, which will move about 500 employees from other offices Downtown.

Building anew, atop almost 250 years of urban history, is more expensive than green-field development in the suburbs. For that reason, the Post-Gazette has no problem with a financing plan that augments $122 million in private money with a generous but wise investment of $48 million in state dollars and city-county tax breaks.

We wish the hotel were a little closer to the David L. Lawrence Convention Center, which certainly could use more hotel rooms nearby: Convention delegates appear loath to walk even short distances. On the other hand, the PNC complex is in position to be a change agent for Fifth and Forbes. It will be right across the street from another ambitious redevelopment project. Madison Marquette, a Washington, D.C., developer, is seeking to persuade merchants like Crate & Barrel and Tiffany & Co. to open stores in its own residential and retail complex. And it will be half a block from Piatt Place, the retail and residential development that will take over the vacant Lazarus-Macy's building.

The addition to the neighborhood of several thousand hotel guests, office workers and condo residents via Three PNC Plaza can only add to the lure of the Madison Marquette and Piatt projects. No wonder Mayor-elect Bob O'Connor has called the past few days the best week for Pittsburgh in a decade.

The time line for construction is ambitious, with demolition slated to start this summer and completion in a little more than two years. That gives historic resonance to the undertaking. When Pittsburgh marked the 200th anniversary of its founding in 1958, the original Gateway Center office towers and Mellon Square park -- both part of the city's first renaissance -- were only a few years old. A fall 2008 opening for Three PNC Plaza would be a fitting symbol of urban renewal on the city's 250th birthday.