The Xanadu project, launched in 2003 to add a major retail center to the New Jersey Meadowlands, was never envisioned as a garden variety mall. But New Jerseyans and visitors driving the N.J. Turnpike got a sense of what it wasn’t supposed to be in what it had become—an odd multicolored warehouse-like structure that stayed unfinished for a number of years and prompted a distinction then as the state’s leading eyesore.

But with new white aluminum cladding, a major redesign, a new name, three developers—and more than $5 billion and 15 years later—the American Dream has arrived.

Now an expanded retail-entertainment complex set to open in stages this year, it includes three indoor theme parks, 450 tenants and a dozen other attractions—far eclipsing the original concept, and with few peers, if any, in the changing U.S. retail real estate market.

And it’s all atop marshland that almost swallowed a Bobcat excavator.

The 5-million-sq-ft project is borrowing from developer Triple Five Worldwide’s own playbook for its mega-retail Mall of America complex in Minneapolis, where 20% of the property features entertainment attractions. The project could include a $250-million plan to build what would be North America’s largest indoor waterpark if it wins over opponents.

Read More