Market Square, not long ago plagued by nuisance bars, drug sales and loitering, rapidly is becoming a Downtown hot spot.

The public square, the city's oldest, is expected to become home to a wine, cheese and dessert bar and a Dunkin' Donuts this spring and summer.

They will join another new restaurant, Moe's Southwest Grill, scheduled to open in summer; the newly opened Crazy Mocha Coffee; and MixStirs Cafe, which opened last fall.

The transformation coincides with a crackdown on illicit activity in the square by the city and the Allegheny County district attorney's office, and the redevelopment of the G.C. Murphy store, which will house apartments, shops and the new Downtown YMCA.

Herky Pollock, executive vice president of CB Richard Ellis, a real estate firm, said the crackdown, the reuse of the Murphy's building and the Lazarus-Macy's store a block away and construction of the Three PNC Plaza skyscraper on Fifth Avenue near the square are having an impact.

"With all the development going on around it, it's taking on a whole new life and people are embracing it with open arms," he said.

The wine, cheese and dessert bar will open in space once occupied by Mick McGuire's, also known as M & M Lounge, which was shut down in January 2007 after a raid and three arrests on drug-related charges.

Dunkin' Donuts will move into space most recently used by Giggles, a variety shop on Forbes Avenue that closed this year after the owner was charged with possession of drug paraphernalia and prohibited weapons.

The new bar, which will be named Sante, will serve French wines, cheese and pastry-type desserts, spokeswoman Tara Rieland said.

"It's a very new concept in Pittsburgh," she said. "There's no such thing. We're excited to create a new niche."

The owner, Brian Price, hails from the Washington, Pa., area, and was attracted to Market Square because it's close to the Cultural District and several Downtown condominium and apartment complexes, she said.

Mr. Price, who was unavailable for comment, expects to open the bar in mid- to late May.

"He believes in Market Square," Ms. Rieland said. "He believes it will be one of the next up and coming areas. He believes in Downtown."

The bar will be "very upscale" with a "definite Paris feel to it," she added. In addition to French wines, customers will be able to sample cheeses from different countries as well as the desserts.

The Market Square Dunkin' Donuts is expected to be the first of 105 being developed in Allegheny and 16 surrounding counties over the next nine years by Heartland Restaurant Group, a locally owned and operated franchisee.

Robyn Frederick, Heartland vice president of human resources and marketing, said the company hopes to open the Market Square store in late June or early July.

It would be part of a new generation of Dunkin' Donuts that serve flatbread sandwiches and pizza as well as the usual array of doughnuts and coffee.

"The restaurant will be the foundation for our growth" as Heartland seeks to expand the Dunkin' Donuts chain in the Pittsburgh region, Ms. Frederick said. She said Heartland saw the Market Square space as a "great site" in the heart of the city.

"I think what made it easy is that we know the city is trying to make changes [to Market Square]. We wanted to be part of that," she said.

Tom Sullivan, a commercial broker with Pennsylvania Commercial Real Estate, believes businesses are moving in to capitalize on surrounding development as it is completed.

He said the addition of Dunkin' Donuts may touch off "a coffee war" with Starbucks, Bruegger's Bagels, Crazy Mocha and Nicholas Coffee Co. in the square. It also could have implications for the venerable Jenny Lee Bakery, a longtime Market Square fixture.

"It might have some impact but nothing we're really worried about," said K.C. Ciganik, a sales clerk at Jenny Lee, adding that the bakery has a loyal following for its cakes and baked goods.

More change could be coming to Market Square. There are plans to remove buses from the square for good this spring. The Pittsburgh Downtown Partnership also expects to add more tables for outdoor dining and is offering matching grants to shop and restaurant owners to spruce up facades and sidewalks.