Kansas City, Mo. ? Standing on what they hope will one day be the home court or ice of an NBA or NHL team, Kansas City civic and business leaders on Friday broke ground on the $250 million Sprint Center.

The arena, to open in the fall of 2007, is considered a cornerstone in the ongoing effort to transform the area from a series of rundown buildings that are mostly vacant at night to a major entertainment/retail center with a new corporate headquarters for H&R Block Corp. and a performing arts center.

Mayor Kay Barnes thanked voters who last summer approved a special sales tax on hotel rooms and rental cars to help pay for the arena.

“It is the citizens who have really made this possible,” Barnes told the audience sweltering under a white tent set up on the construction site. “This is another major step forward in the revitalization of downtown Kansas City.”

The big question is who will call the Sprint Center home when it’s completed. While an arena football team has signed on to play in the 18,000-to-20,000-seat arena, officials have yet to ink a deal with a top-shelf basketball or hockey team.

“We’re going to do everything to bring one here,” said Tim Leiweke, president and chief executive of Anschutz Entertainment Group of Los Angeles, which is contributing $50 million to the project and will manage the arena.

Leiweke also shrugged off concerns that price hikes for construction materials and a scaled-back redesign of the arena signal the center will be more functionary than fabulous.

“The arena is going to be beautiful outside and even better inside,” he said, adding that the National Basketball Assn. and National Hockey Assn. have both signed off on the latest blueprints as meeting their requirements.

Sprint Corp., the telecommunications company in nearby Overland Park, Kan., is paying $2.5 million a year over 20 years for naming rights to the center.

Sprint CEO Gary Forsee promised the crowd that while Sprint’s headquarters will move to Virginia, if it completes its upcoming merger with Nextel Communications Inc. later this summer, the company will make good on its promise.