CHICAGO (CBS) — Dozens of radio and television pioneers got together Tuesday night in Chicago to celebrate the history of broadcasting.

CBS 2’s Mike Parker reports it was a pre-opening celebration for the new version of the Museum of Broadcast Communications at State and Kinzie streets.

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It’s huge, expensive, and a monument to America’s electronic history. It opens officially on Wednesday but contributors and friends and legends of the art and business of radio and television came together for a sneak preview.

Museum founder Bruce Dumont said, “It’s a long time coming, which means we can celebrate for a long, long time as well. The hurdles are behind us.”

Inside, almost 20,000 square feet of exhibits were on display, celebrating everything from WGN’s “Bozo the Clown” to the television shows of the past 60 years; the comedies and the variety shows. It is a kaleidoscope of history in both color and black and white.

Chicago actor John Mahoney was on hand.

“This is amazing,” he said. “You could spend days wandering around, and I just keep seeing new things that you want to look at. It’s a great place.”

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Veteran TV news host Hugh Downs talked about how working in the medium enriched his life.

“I got access to things and situations, and meeting people, and so forth — that if I had been an eccentric billionaire, I couldn’t have bought my way into,” Downs said.

The museum features exhibits of the broadcasting moments that changed TV and radio – and beyond. There’s the old CBS camera used in the Kennedy-Nixon debate at the WBBM-TV studios in 1960.

Dumont called that broadcast, “the single most important television show ever to come out of Chicago, and from that moment on, television and politics in America were never the same again.”

Dumont also said he was stung by a Chicago Tribune story suggesting that he over-promised the number of jobs the project would create.

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“It’s amazing that a news organization doesn’t understand economic development,” he said, calling the Tribune’s story, “vindictive.”