Good bye, Plaza. So long, Court.

At 9:45 a.m. Thursday, King of Prussia Mall was officially declared "one mall" by owner Simon Property Group.

Hello Bonobos and Calligaris.

Bring it on, Jimmy Choo, Vince, and CH Carolina Herrera.

The East Coast's premiere shopping mall just grew by about 500,000 square feet. It now includes a 155,000-square-foot connector that ties together the two former sections for the first time, and an added 250,000-square-foot wing, home to 50 new retailers and restaurants.

The expansion that started 30 months ago was capped Thursday with a ribbon splicing, not a cutting: Two ribbons from each mall were joined at Savor King of Prussia, the mall's new food court with WiFi stations and fountains throughout.

"King of Prussia has reached new heights," said Rick Sokolov, Simon's president and chief operating officer, just moments before the ribbon ceremony. "I think we have come up with a collection of retailers that people would find compelling."

Those stores opening Thursday included Cartier, Altar'd State, and David Yurman.

The mall last year attracted 25 million visitors, about the same number as Atlantic City's beaches and casinos.

"But we're not done," Sokolov said. "We invest in our properties and we're always thinking about what's next."

"The retailers here are just crazy," said Spencer Rubin, 30, owner of Melt Shop, which offers grilled sandwiches and shakes to go and opened Thursday next to the new Hai Street Kitchen and across from Club Monaco. "We are very happy to be here. We were just lucky to have been involved with two other Simon developments [in New York] to land this prime spot."

While the corpses of brick-and-mortar stores have piled up the last few years with the advent of digital shopping, KOP Mall has had a different problem: keeping up with the demand of elite retailers who want to occupy its spaces or expand into bigger storefronts.

Simon executives say that rising demand was the primary reason for the $250 million expansion.

"The King of Prussia Mall has been very successful over the years because it has been able to reinvent itself as new trends emerge," said James Cook, Americas director of research, retail, for Jones Lang LaSalle. "The fact that this new expansion brings with it appealing fast-casual dining options like Shake Shack along with new-to-market retailers and a compelling modern atmosphere means that local shoppers will have yet another reason to visit and spend."

An ad campaign launched in the Philadelphia and Washington areas on Wednesday spread the word that the mall is now one big, unified spectacle since debuting 53 years ago.

The TV spots will air in both markets for the next three weeks.

"We're fortunate to have some of the best shopping in the United States right here in Philadelphia's backyard: Montgomery County," said Ed Harris of the Valley Forge Tourism and Convention Board, which is behind the new ad campaign.

The expansion brings the total retail square footage in the King of Prussia area to 6.3 million.

The upgrade has been credited for spurring more than $750 million in construction nearby for residential and office uses to handle the influx of thousands of new workers. The first ground-up commercial office building in a decade is set to open in the nearby King of Prussia Business Park.

At the same time, a cluster of luxury apartments, stores, and eateries is sprouting at the Village at Valley Forge and at the $100 million King of Prussia Town Center.

SEPTA is proposing to extend the Norristown High Speed Rail Line so it would have at least two stops by the mall and two more in the business park. If approved, the $1.1 billion project could open in 2023.

By 1 p.m., the new corridor was nearly packed with shoppers.

Maureen Loesberg, 66, of Valley Forge, made full use of one of the WiFi recharging stations inside Savor, the food pavilion. "I love this," she said.

Ryan Shing, a 19-year-old Drexel student, marveled at all the new stores. "It will make for a more enjoyable walk, especially when it's really hot and really cold out," Shing said. "It's a big deal."

Then there was Dorothy LiCalizi, who said she is in her 60s, and plans to move back to Philadelphia in the spring from Santa Monica, Calif.

She was in town visiting friends and seeking job leads. She was impressed with how the mall had evolved. "All the skylights and store finishes are so modern," she said. "I will miss the shopping in L.A., but this is what I came for.

"Everything's here."

215-854-4184 @SuzParmley