With 75 percent of the condos in his 151 First Side building Downtown sold, Ralph Falbo is ready for an encore.

He is one of four developers to submit a proposal to Allegheny County to buy the One Smithfield Street building and an adjacent parking lot Downtown at the corner of Smithfield Street and Fort Pitt Boulevard, only a few blocks from his 151 First Side complex.

He has plans to develop a boutique hotel and another 120 condos at the Smithfield Street site, so confident is he of the market for Downtown living.

"I just feel good about what we did here and the response," he said. There were people who wanted to be in [151 First Side] and couldn't afford it. I think there's an untapped market out there."

Mr. Falbo said he would offer condos in the $200,000 to $300,000 range, which proved to be the quickest selling units at 151 First Side, where prices run from $200,000 to $1.8 million for an 18th-floor penthouse overlooking the Monongahela River.

He would use the parking lot for the condos and the hotel. The One Smithfield Street building would remain as office space.

The building recently caught the attention of a panel of experts from the Washington D.C.-based Urban Land Institute. The group, which was in town to help Point Park University plot its development, suggested that the school move its Pittsburgh Playhouse from Oakland to the building, as part of an "iconic theater complex."

Mr. Falbo said he would like to talk to the university about a possible partnership.

"If they can't own it, I thought they might like to be in it," he said.

Dennis Davin, the county's economic development director, would not release the names of the other three developers to submit preliminary proposals, but said their plans involved condos or apartments.

The county received those proposals about the same time the Urban Land Institute panel finished up its work. So far, Point Park has not offered a plan. Mr. Davin said the county also has received interest from other developers who thought the time period for submitting proposals was too short and didn't file.

As a result, the county is still trying to decide whether to go with the four proposals it already has or put out another request to developers.

Mr. Falbo is hoping to build off the success of 151 First Side, Downtown's first new condominium building since 1968. He has sold 62 of 82 units in the high rise, with the bulk running from $350,000 to $450,000. About 23 buyers have moved into the building so far. Forty percent of all buyers have been from out of town.

"We're just happy as hell," Mr. Falbo said Tuesday morning before leading County Chief Executive Dan Onorato and Mayor Luke Ravenstahl on a tour of the complex during its grand opening.

Both politicians said the 151 First Side project has helped to usher in a residential renaissance Downtown. Luxury condos also are being developed at the former Lazarus-Macy's store, the old Union National Bank, and Three PNC Plaza, the new 23-story skyscraper under construction.

"This project was key because it was the first new one in a long time," Mr. Onorato said. "If this didn't sell, it would have put the brakes on Downtown new housing. But just the opposite has happened. This is now being viewed as, 'wow, there's a market, there's a market to service here.' "

Mr. Falbo also is planning to develop 40 condos on the South Side near the UPMC Sports Performance Complex.