It could be one big irony: The project that's designed to rejuvenate Market Square could be helping to kill off some of its businesses.

One restaurant has closed, another could be on its way out, and a third is struggling to hang on as the square's construction, coupled with the recession and the G-20 economic summit, takes its toll.

The 1902 Landmark Tavern, facing back rent and sewage bills, shut down at the end of the day Wednesday after 28 years in Market Square.

General manager Marty Mariani said Thursday the restaurant held out as long as it could amid the square's ongoing construction, but could last no longer. The subway work that has affected nearby Stanwix Street hasn't helped, either, he said. The closing has left about 30 people without jobs.

"We pretty much knew it was coming if we didn't have a miracle happen in January," he said. "We've been trying to stay afloat but it all caved in eventually."

Mr. Mariani said the square's construction, which started in August and is aimed at transforming the space into a European-style piazza, cut deeply into the restaurant's dinner business.

"You can't survive just on lunch," he said.

He added the restaurant also lost about $20,000 during the week of the September G-20 economic summit, which closed off much of Downtown. The restaurant, he said, "didn't get anybody in the whole week" and closed early the second day of the summit.

"Since the G-20, we really haven't been able to keep our heads above water," he said.

A couple doors down, Costanzo's restaurant could be facing a similar fate. Owner John Costanzo Jr. said he could be out of business in two weeks unless he gets rent relief or financial help.

Between construction in the square and rehabilitation work on three buildings near the restaurant, "It's been a nightmare," he said.

Costanzo's has been in Market Square for four years after spending 33 years on Fourth Avenue. It has been Downtown for more than half a century, Mr. Costanzo said.

"We've watched people come and go and we're still here. But we're not going to be here for long," he said.

Mr. Costanzo said things have gotten so bad that he has to choose between paying the electric bill and buying food for the restaurant. He approached the city for financial assistance, but to no avail.

"If someone doesn't help us we're done," he said.

Across the street, one of the newer restaurants in the square, MixStirs Cafe, had considered closing but decided to "tough it out," co-owner Michael Pfeuffer said.

"We're not out of the woods. But we think we have a solid plan to get through this. We don't plan on closing," he said.

To stay afloat, MixStirs has gone from eight employees to one. Mr. Pfeuffer said he hasn't taken a salary in a year. Were it not for the "generosity" of MixStirs' landlord, "we'd be closed," he stressed.

The business, Mr. Pfeuffer noted, was doing well when it first opened. In fact, it was one of the first to receive a Pittsburgh Downtown Partnership grant to improve its facade.

But construction in the square, as well as that on the subway and nearby Forbes Avenue, have brought down business, he said.

"Once the construction started, it was like hitting a brick wall," he said.

The G-20 only made things worse.

"It was a complete absolute business killer. It's another thing that got lumped on top of us," he said.

Mr. Pfeuffer said businesses might have been better off if the city and the Pittsburgh Downtown Partnership had stuck with a plan to redo the square in sections rather than all at once.

"I think that would have been less intrusive to business operators," he said.

Mike Edwards, the partnership's president and CEO, said officials, in consultation with square merchants, decided to do the renovation all at once because it would take 11 months as opposed to 18 doing it by sections.

He called the 1902 restaurant closing "unfortunate." He acknowledged that the square's construction has had an impact on some businesses. The partnership, he noted, has tried to lessen the impact with promotions, a blog, and Facebook entries.

"Any time there's construction, you're going to have some impact on businesses," he said. "The ones with strong business models will survive."

Not all Market Square businesses are sinking, he said, noting, for example, that the Oyster House was full when he ate there Thursday.

In addition, Nicholas Coffee is seeing steady business, owner Nick Nicholas said. Primanti Bros. restaurant, which he co-owns, also is holding its own, he said.

"We kind of defy logic, I guess. We do well all the time. A lot of that has to do with the institution of Primanti's in Pittsburgh and the current publicity we've been getting on the Travel Channel and the Food Channel," he said.

Mr. Nicholas, who owns the building the 1902 restaurant is vacating, said he already is looking for someone "with experience and a clear view of what to do with the space" as a replacement.

Mr. Mariani and the owners of Costanzo's and MixStirs believe restaurants will thrive in Market Square once the construction ends in June and more outdoor dining becomes available.

For the latter two, it's a matter of hanging on to reap the benefits. For 1902 Landmark Tavern, it's too late.

"It's a damn shame," Mr. Mariani said. "Someone's going to come in and have a great opportunity to do well."

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