During a groundbreaking ceremony Wednesday to mark the start of a $30 million expansion and renovation of the Minnesota Children’s Museum, officials made sure to thank all of the big shots who helped raise the needed money: Target, Best Buy, 3M, the state of Minnesota.

And Arthur Beck.

Museum bosses made a big deal of the $10 the 4½-year-old Bloomington boy chipped in to a project that will add 35 percent more space — including new galleries, a multistory climbing structure and a cafe — to the downtown St. Paul facility. In honor of Arthur’s generosity, officials took his picture, thanked him enthusiastically and gave him his own mini tool belt to help with the construction.

“Thank you,” the boy said before racing off in search of fun.

Play — unstructured, creative, energetic play — is exactly what the project will promote and enhance, officials have said.

On Wednesday, with $28.5 million of the construction cost now raised — including $14 million from the state, $1 million from the city of St. Paul and $13.5 million from corporations, foundations and individuals like Arthur — the project was launched.

“It’s been a long road, and more meetings than you could possibly count,” said Dianne Krizan, museum president. “But we’re here — and we’re officially starting construction!”

Gov. Mark Dayton, himself a former Children’s Museum board member, was on hand to proclaim Wednesday as a statewide “Day of Play.” Play is what the governor remembered his sons doing at the first children’s museum in Minneapolis’ Warehouse District. “We heard a lot of ‘No,’ ” Dayton said of early fundraising efforts. “People asked ‘What’s the need for this?’ But play is so important.”

Play, too, is what board member Taylor Harwood remembered as a 5-year-old in a mostly empty museum in St. Paul’s Bandana Square. His mother, Marialice Harwood, one of the museum’s founders, would bring him and his brother along to evening meetings. “We had the whole museum to ourselves,” he said. “It was great.”

The project will expand the museum from 65,000 to 74,000 square feet, and add bathrooms, an elevator and a skyway-level entrance. The number of permanent galleries will increase from six to eight.

Work is expected to be completed in January 2017. The museum will mostly remain open, closing only for a few months in late 2016. More than 450,000 people visit the museum each year.

On Wednesday, DJ Jay Diggs delighted dozens of children and grown-ups as he danced to music while they batted around beach balls and stacked little white boxes as part of a “ground-shaking” ceremony. While that was going on, young Arthur had retreated to a back gallery — to play.

His mother, Claudia, said he became inspired to donate his birthday money and other funds he’d collected after seeing photographs of what his favorite museum could become. “He thought it was so cool,” she said. “And, when we told him they needed money to make it happen, he wanted to do it. He’s so excited about it.”