Held hostage for a year by hope that they might snag a casino license, two pieces of prime central Philadelphia real estate lost that gamble this week - but may yet cash in, as all eyes await Plan B for both locations in a hot downtown market.

Developers who had proposed casinos at Eighth and Market Streets and the former Inquirer Building at Broad and Callowhill Streets said they had no alternate plans after learning Tuesday that the city's second gaming license would instead go to a site near the sports arenas in South Philadelphia.

But with new apartment and retail development deals being inked virtually every week in and around Center City without public subsidy, it should not be long before new plans are hatched for both, as long as property owners agree to quick action, officials and market watchers said.

One top city official said market conditions were so favorable to development that the Nutter administration would have little patience if movement were not swift at one of the locations, which has remained inert for two decades as repeated plans have fizzled: the open-air lot at Eighth and Market owned by Ken Goldenberg and other investors.

"I want to see it move forward now. They need to be moving right now," said Alan Greenberger, deputy mayor and commerce director. "We will apply whatever pressure we can to get them to move quickly."

For the tower-topped former Inquirer Building and adjacent multistory parking lot, owned by Bart Blatstein, coming up with attractive redevelopment plans may be a bit more involved, given the character of an edifice that once housed printing presses in its cavernous bowels.

But, as with Eighth and Market, vitality and redevelopment in the neighborhoods surrounding it, including the soon-to-come new Comcast skyscraper, should generate prospects for Blatstein's roughly seven acres of assembled land, Greenberger said.

"Bart's a creative guy," the deputy mayor said. "He's going to have to apply some of that creativity here."

Blatstein, who helped reengineer Northern Liberties into a funky urban hot spot, said Friday that he had spent no time imagining a need to turn his property into anything but a casino and entertainment complex.

"You don't go into a race thinking about losing," Blatstein said Friday. "I just have to sit there and spend some time. I'm going to chill out for the weekend and then jump on it next week."

Goldenberg, through a spokeswoman, declined to be interviewed. He has said he would consider many potential options for Eighth and Market.

One major reason for optimism that speedy alternatives may emerge: Investors are pumping money into central Philadelphia by the billions of dollars.

Retailers who might have shown zero interest in Center City even five years ago are scouting for sites as young residents and affluent baby boomers move into newly developed apartments and condos.

Those condos and apartments are being built by investment firms and pension funds that envision better returns in real estate than equities. Retailers are key for anchoring new projects with high rents or the promise of drawing lots of foot traffic.

"I know the tenants that are out there, and many of them have not found a home," said Larry Steinberg, a Center City retail specialist at real estate brokerage CBRE/Fameco.

Steinberg said smaller specialty retailers were trolling for locations and, in some cases, being fought over by competing development proposals along Market Street East.

But other chains are searching for large store footprints: 25,000 to 50,000 square feet, which could bode well for a location like Goldenberg's or Blatstein's.

One such retailer, which Steinberg would not name but said was not a grocery chain, approached CBRE a month ago about finding a 60,000-square-foot space in Center City, and would consider repurposing multiple floors of an existing building if need be.

Also in play: CBRE is representing a movie theater chain "that would have a potential interest in Eighth and Market," Steinberg said.

Steinberg said he fielded a call from someone on Goldenberg's team the day before the casino license was awarded to Cordish Cos. and Greenwood Gaming & Entertainment Inc.

"They're just now starting to think about it," Steinberg said of Goldenberg's considering alternatives to a casino. "They were hinting at residential development . . . maybe mixed use. They wanted some information we had on the residential density in the area."

Goldenberg's parcel is surrounded by developers already making headway. Block-long redevelopments are underway on Chestnut Street and Market between 11th and 12th Streets, and plans to overhaul the Gallery are in the works.

With such competition for retail tenants, and so many apartments being built, is there room for much more?

Thomas Jefferson University Hospital could fuel additional demand, Greenberger said. Having recently bought naming rights to the former Market East commuter rail hub beneath the Gallery, and newly exited from a partnership with a suburban hospital network, Jefferson could be positioning itself for a greater footprint near its Washington Square-area campus.

Blatstein, meanwhile, believes he can take his time.

He said that he paid $22 million in 2011 for the Inquirer Building and its parking garage, and that its value has doubled.

"I've received three phone calls from credible groups that want to buy it," Blatstein said Friday, adding: "I'm in no rush."