A New York auctioneer said yesterday that it would take bids for the Old City site of a proposed 33-story, 236-unit luxury condominium development that has not progressed beyond the planning stage.

The waterfront site is at 412 N. Front St. It is already approved for a project of nearly 322,000 square feet of residential units, 4,095 square feet of retail space, and 65,049 square feet of common space.

The site is owned by 412 North Front Associates, a partnership that included developer CNO Properties of Philadelphia. The partners declined to comment about the sale, which comes amid softening in the city condo market.

Kevin C. Gillen, a Wharton School economist who monitors the local housing market, said the site's waterfront location was a plus because the neighborhood had not yet been oversaturated with condo developments.

"We haven't seen the level of luxury condo development in Old City that we've seen in other parts of Center City," he said. "The essential fundamentals of the location appear to be good."

However, Gillen said, the overall residential real estate market is a challenge.

"We have flat prices, rising inventories and dropping sales," he said. "The numbers are even worse for the condo market. We haven't seen any serious declines in prices." He said the turnover rate for condos was about a third of what it was last fall.

The auctioneer had a more positive take. "The reason they brought us in was that the timing made sense and because the property is difficult to value because of its uniqueness," said Steven L. Good, chairman and chief executive officer of Sheldon Good & Co. Auctions Northeast L.L.C., which is conducting the sale. "They've taken it as far as they planned to take it, and so basically, they're now asking us to find a developer to build the property."

Good said his auction firm would accept sealed bids for the property, at a reserve price of $13 million, on June 13.

The company said the sellers had projected revenue of $164 million on the project.

Good said yesterday that the response to the announcement had been strong.

"Obviously, a property of this size and location doesn't become available very often in a marketplace like Philadelphia," he said. "It's a national response, both from the general Philadelphia marketplace, as well as outside the region.

"The size of the project is drawing in some very significant players," he said. "What they will ultimately do with the site remains to be seen."

Good said the condos were to include one-, two- and three-bedroom units, each with a terrace. He said the site afforded great views of downtown and the Delaware River.