Like so many American men, Dr. Nicholas DePace collected baseball cards in his youth. Unlike most, however, he never stopped accumulating sports memorabilia. Never.

Today, DePace (pronounced de-PA-chee), 62, is the owner of what is arguably one of the world’s largest and most valuable private sports memorabilia collections. Covering a variety of sports including boxing, NASCAR racing and golf – in addition to the “big four” – it boasts several million-dollar-plus items, among them a 1903 Honus Wagner T206 baseball card considered the most coveted of all and the document granting baseball immortal Joe DiMaggio and film icon Marilyn Monroe their divorce.

Before this year, you had to be a friend of DePace’s to get a glimpse of his treasure trove of relics. But in January, he opened the DePace Sports Museum and Library of Champions in a converted bank building on Collingswood’s bustling main drag, Haddon Avenue. Visitors can tour the collection from noon to 5 pm Tuesday through Thursday, and noon to 9 pm on Friday and Saturday. Admission is $10 (children under 12 are admitted free). It is, says the museum’s namesake, unusual among such facilities.

That it just doesn’t focus on one sport in the manner of a hall of fame “is what makes this such a different sports collection,” offers the Haddonfield resident, who is also a cardiologist. “Nobody I know of diversifies like this in the whole world. I don’t know anyone who has a huge boxing collection, a huge baseball collection, a huge football collection…hockey, golf, soccer.”

Planning for the nonprofit museum began in earnest about four years ago. But its genesis dates back considerably longer, to when baseball was DePace’s sole focus.

“Joe Frazier was my dearest friend, a patient for 30 years,” he says of the late, Philly-based heavyweight boxing legend. “We developed a strong bond. Joe said to me in the late 1980s, ‘The bats and uniforms and cards are nice, but it’s not the whole world. I fought all over the world. People in Manilla may not like baseball.’ So we branched out.”

“Joe wanted me to open up a ‘Museum of Champions.’ I loved the boxing game, so I started collecting boxing things. Then I started collecting for the other different sports, figuring one day, I’d open up a ‘Museum of Champions’ to immortalize these people and keep their memories alive and be inspirational to young people. That’s how it started.”

Many of the sporting world’s greatest names are represented in the individual displays that cram every available inch of the 4,500-square-foot space on the building’s first floor, most notably via scores of game-worn jerseys. Not surprisingly, the focus is on teams, owners and players who have represented Philadelphia through the decades.

“When you go to the museum, you’re just seeing maybe about 15 percent of what we have,” says DePace, a North Jersey native who grew up rooting for the New York Yankees. “And I heavily front-loaded it with Philadelphia things. I could have easily filled it with Los Angeles things or New York things.”

Perhaps the most puzzling aspect of the collection is the attention paid to former Washington Senators and Minnesota Twins slugger Harmon Killebrew, whose Hall of Fame career had virtually nothing to do with Philadelphia.

“Killebrew,” explains DePace, “was my idol growing up. He was my favorite baseball player. I gave him a little corner just for myself.”

The items are arranged in visually arresting fashion behind floor-to-ceiling walls of Plexiglass, with the multi-hued uniforms creating an explosion of colors as soon as people enter the facility. Currently, DePace’s most valuable items cannot be seen at the museum because of security and insurance issues. But the doctor promises such memorabilia will ultimately be on view, if only for limited engagements.

According to museum curator Eric Katz, while the repository is up and running, it remains a work in progress.

“What we’re missing is the technology,” admits Katz. “The biggest thing is you need the technology, like iPads that explain the individual items. People should be able to pick up an app when they come through the door and follow it on their phones. And there should be at least 20 video monitors. It’s all in the works, but you can’t do everything at once.”

According to Katz, the museum’s appeal depends on the individual visiting.

“A lot of it is the memories,” he says. “I see a lot of the older people come in here; it’s very nostalgic for them. It brings them back to a time in their lives that was easier, and they were younger. You definitely see the smiles on their faces, especially the older men who walk through here.”

“For the children, there’s an education role that we serve: The whole thing about sportsmanship and fair play.”

The DePace Sports Museum and Library of Champions may be about nostalgia, education and celebrating excellence in a realm that is so important to so many people. But, according to DePace, it is also about providing optimism for the sports fans of the Delaware Valley who these days, he contends, are awash in despair over their professional sports franchises.

“People are depressed about the current state of Philadelphia sports – it’s the worst it’s ever been in history with every sport,” he says. “But they can go to the museum and see what the potential is. It brightens people up. They feel good when they come out.”

“People are dying for championships now. Maybe if they go to the museum, they’ll be patient, knowing we have a great heritage of sports championships. Things will come in time with patience. We’ll get some more championships.”

“This tells you there was greatness in the past and potential in the future.”