The towers, which opened in 2001, already have 304 luxury condos that were initially priced from $500,000 to $6 million, said Anthony Pangaro, principal of Millennium Partners-Boston, the project's developer.

The towers include a hotel and the Phillips Club -- apartments renting from $4,500 to $6,000 a month. They'll go on sale as condos in late summer.

Many large developments are built in phases, but the Ritz was built all at once in the hope that it would quickly transform a marginal area near the old Combat Zone, Pangaro said. As a result, the Ritz is larger than a typical new Boston luxury tower of about 100 condos or fewer. With a project so big, the challenge was to avoid saturating the market, and a decision was made to spread the condo sales over several years.

Part of that plan was to set aside several floors as the Phillips Club, which targeted out-of-town executives visiting Boston for several weeks or more to spend time at their corporate headquarters.

But soon after the opening, the economy slumped, and acquisitions reduced the number of Boston headquarters companies. That meant less business than expected for the Phillips Club, Pangaro said.

Still, the plan always had been to consider converting those units to condos once the original Ritz condos were nearly sold out, Pangaro said. About a dozen remain available.

No prices have been set for Phillips Club units. Since they're smaller and on lower floors than most of the condos in the complex, they will cost less.

At Listing Information Network, which tracks downtown condo sales, president Debra Taylor Blair said the conversion of Phillips Club apartments is well timed.

''Demand for new-construction luxury condos is high," she said.

And the Phillips Club condos will hit the market before some luxury developments now in the pipeline are completed, she said.

One building that recently opened is Millennium's One Charles, on Charles Street near the Ritz. It's about three-quarters sold, said Pangaro, who added that all condos comparable in size and price to the Phillips Club units have been sold.

''We won't be competing with ourselves," he said.

Chris Reidy can be reached at reidy@globe.com.