Indiana billionaire Bill Cook, who founded a medical-device business that made him a fortune, poured millions of dollars of his personal wealth into restoring luster and life to some of the state's fading historic buildings.

The Cook Group founder didn't want to save old buildings just for sentimental reasons. Colleagues who championed some of those projects say Cook began each restoration contemplating what practical use each newly polished structure might serve, and how it might spark development around it.

"He didn't restore buildings just to restore them and have a beautiful, empty building sitting around — he wanted something that was occupied and used by the public. He was interested in old things, but he wanted them to be workable," said Jack Mahuron, a member of Friends of Beck's Mill.

The business sense from his corporate work carried over into his restoration projects, said those who spent the past week remembering Cook following his death April 15 at age 80. The Herald-Times estimated about 5,000 people attended a public visitation Saturday at the company's global headquarters in Bloomington.

Mahuron said Cook made it clear when he offered $1.2 million to restore Beck's Mill that the refurbished water-powered grain mill near Salem, Ind., needed to make money.

The retired Salem banker said the revived mill, which was built in 1864, has met that goal since it was rededicated in October 2008, complete with a new water wheel powered by water flowing from a nearby spring-filled cave.

He said the revenue the mill about 30 miles north of Louisville, Ky., generates through admissions fees and the sale of cornmeal ground by its millstones covers its annual expenses.

"It's self-sustaining, and that's what Mr. Cook wanted," Mahuron said.

Cook was Indiana's wealthiest resident with 2010 holdings estimated by Forbes at $3.1 billion. The Cook Group, which boasts diverse medical device companies, had its origins in 1963 when Cook began making catheters in the spare bedroom of the Bloomington apartment where he and his wife then lived.

By the 1970s, the company's success allowed Cook to begin indulging his passion for historic preservation.

Cook Group spokesman Dave McCarty said that during the past three decades, Cook, wife Gayle and the company have spent more than $156 million on a laundry list of historic preservation projects around the state.

The first restoration project Cook was involved in was the Colonel William Jones Home, an 1830s Federal style home in Gentryville, Ind., where Abraham Lincoln worked as a boy and which the Cooks later donated to the state of Indiana.

With each restoration he tackled, Cook became involved in the finest details of each restoration project, even choosing paint colors and window styles, said Jim Murphy, president of CFC Properties, Cook Group's property development and management division.

"When many people would look at an old building they might see only its challenges, he would see the opportunities. And I think that's what set him apart from many people. He had a vision," he said.

Tina Connor, executive vice president of the Indianapolis-based preservation group Indiana Landmarks, said Cook was a driving force in helping revitalize Bloomington, beginning in the 1970s when he began restoring building around the city's courthouse square.

Over the years, Cook's investment transformed what she said had been a "shabby" downtown into the city's current busy commercial and retail center.

"It was a conscious desire to improve the livability of the core of the city," Connor said. "I think he saw it as a practical approach to take — to fix things and reuse them. Why waste perfectly good things?"

Cook's biggest undertaking was the $55 million restoration of two 19th-century hotels that have brought new jobs and life to the small southern Indiana towns of French Lick and West Baden Springs, which between them have about 2,800 residents.

Cook paid to restore the hotels—and he helped fill them by creating a nonprofit foundation that partnered with a developer to win a state riverboat casino license for French Lick.

Residents of the two towns about 40 miles southwest of Bloomington owe Cook a debt of thanks for restoring the hotels and developing the casino, said Barry Wininger, a member of the French Lick Town Council.

He said those projects created nearly 2,000 new jobs and helped revive the town, which had been fading as local woodworking plants jobs shifted overseas.

"It was to the point where people were wondering, 'What's going to happen down here?'" Wininger said. "His vision really revitalized this whole area down here."

Marsh Davis, the president of Indiana Landmarks, said the roughly $37 million Cook spent renovating the West Baden Springs Hotel after his preservation group saved the 1902 hotel from near collapse in the early 1990s created a building he calls an opulent "jaw-dropper."

Visitors to the six-story hotel enter a 100-foot-high atrium capped by a 200-foot-wide dome that was the world's largest free-span dome until the Houston Astrodome opened in 1965.

"All the projects have been wonderful, but the West Baden project is the star that all the other ones have their orbits around," Davis said. "That was an act of heroism on his part, and I think people are so grateful that he saved that."