MINNEAPOLIS, July 24 (UPI) -- Minnesota's Mall of America amusement park was once the folksy Knotts Camp Snoopy, then the drab Park at MOA and now the big-sounding Nickelodeon Universe.

Nickelodeon Universe, the name of the re-branded and reinvented theme park, features characters likely to appeal to tots and teens: Dora the Explorer, Diego, Avatar, Danny Phantom and SpongeBob, the St. Paul Pioneer Press reported Tuesday.

"It's a big name for a big concept," Howard Smith, senior vice president of Nickelodeon Recreation, said of the park's new moniker. Nickelodeon signed on as the new theme park brand in March

Changes in the nation's largest indoor family amusement park go beyond the name and cast of characters. Mall of America, located in the Minneapolis suburb of Bloomington, is investing about $30 million in improvements, including new rides, healthy food options and a high-tech ticketing system.

"One of our goals is to extend the age and popularity of the park," said Maureen Bausch, MOA's vice president of business development.

Construction begins Aug. 27 with work to be completed in sections so 80 percent to 90 percent of the park remains accessible at all times. Nickelodeon Universe is to be completed in March.