By Janet Moore

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.