Even before the Mall of America opened almost 22 years ago, its second phase was the subject of speculation.

On Tuesday, that retail guessing game concluded once and for all, with mall officials announcing a luxury 342-room JW Marriott hotel, an office tower and more than 50 shops and restaurants aimed for an unassuming concrete patch on the Bloomington behemoth’s northern flank.

The new $325 million iteration of the nation’s biggest shopping mall and one of the country’s top tourist destinations is expected to debut in August 2015.

“We continue to reinvent ourselves,” said Paul Ghermezian, chief operating officer for mall owner Triple Five Worldwide, and the son of one of the mall’s original founders, Bahman Ghermezian. “I like to think of my family as dreamers, but we’re also doers.”

Ghermezian and others spoke at a 30-minute “groundbreaking” Tuesday in the Mall’s rotunda, an event that involved multicolored confetti being tossed with ceremonial shovels, rather than dirt — a nod to Minnesota’s unpredictable March weather.

The expansion — dubbed 1C — will be the mall’s largest since it opened in 1992 as the brainchild of the colorful Ghermezian family of Canada. Previous expansions have been more incremental than fantastical concepts — including the Ikea store, which is almost 10 years old, and a swanky $138 million Radisson Blu hotel that opened last spring.

This project will remake the mall’s current drab and unassuming entrance into a “front door” and luxe plaza off Lindau Lane, which is undergoing a $49 million submersion to make way for the new shops, offices and hotel.

The $106 million 14-story JW Marriott hotel will be connected to the mall by skyway and owned by the Shakopee Mdewakanton Sioux Community, which is financing the lodging component of the expansion. The community operates the Mystic Lake and Little Six casinos in the Twin Cities area, but tribe and city officials say a casino is not in the mix for the Mall of America.

“This is a good investment in an important and healthy sector of Minnesota’s economy, and it will bring jobs to many people who need them, including those in the Native American community,” said Shakopee Mdewakanton Sioux Community chairman Charlie Vig.

JW Marriott, the hotel chain’s luxury concept, will include a full-service restaurant and bar, grand lobby with another bar, fitness center, pool, meeting space and a ballroom that will open in October 2015. When asked how another hotel at the mall will affect Radisson Blu, spokesman Ben Gardeen at the Blu’s parent company, Carlson Rezidor Hotel Group in Minnetonka, declined to comment.

It’s unclear who the actual retail and restaurant tenants will be at this point, but several themes emerged for the 163,000 square feet set aside for shopping and dining. The first level will be devoted to luxury and “aspirational” tenants, the second level to home-inspired merchants, and the third floor will have a food hall, as well as upscale full-service restaurants and fast-casual eateries. An event atrium, larger than the mall’s current rotunda, will be located between the hotel and office components.

“There are so many retailers who are currently not in the market who want to be here,” said Maureen Bausch, the mall’s executive vice president of business development. One potential tenant may be Pirch, an experiential kitchen-bath-laundry room store that bills itself as “a retail pioneer that has brought sweeping change to the appliance and plumbing industries.” (No lease has been signed yet.)

Tenants for the 180,000-square-foot, seven-story Class A office tower have not been announced, either. Triple Five Worldwide Senior Vice President Kurt Hagen said occupants will likely complement the mall’s culture — such as marketing, hotel or retail firms with national or international reach.

David Brennan, a marketing professor at the University of St. Thomas, is a fan of the mall’s expansion plan, but says the office component is the “softest part.” “There may be tenants out there, I’m not sure how many,” he said.

About $34 million in tax-increment-financing will be used to construct the 600-space underground parking garage, utility connections and some surface streets, Hagen said.

Some 1,000 jobs are expected to be created during the construction phase of the project, and 2,500 permanent jobs from retail, hotel and office operations.

Golden Valley-based Mortenson Construction is building the expansion, after Minneapolis-based Ryan Cos. dropped out. (Ryan officials were not available to comment.) Mortenson also built the 500-room Radisson Blu at the mall, and is currently erecting the $1 billion Vikings stadium in downtown Minneapolis.

When asked whether the construction timeline for completion of the project by fall 2015 is aggressive, Mortenson executive Lander laughed. “We have repeatedly been able to deliver complex projects on challenging timelines,” he said.

Future expansions for the mall will creep onto existing surface parking lots on its north side, but they will depend on financing. The city of Bloomington has approved plans for a water park, dinner theater, more hotels and office space and perhaps residential units.