BALTIMORE (WJZ)– Baltimore is rich in baseball history, and now our city is playing a role in what’s being called the most exciting find ever in the history of baseball card collecting.

Mary Bubala has the story.

Something remarkable happened to Karl Kissner in this attic after he and his family inherited the turn-of-the-century house in rural Defiance, Ohio, passed-down by his aunt after her recent passing.

What he found were the unassuming little baseball cards, about 700 in all. They’d been tied in a neat bundle and put in a cardboard box, sitting untouched for 100 years.

Kissner didn’t know exactly what he had but the sports collectibles experts at Heritage Auctions in Texas did.

“We believe this is the most significant find in the history of the hobby,” said Chris Ivy of Heritage Auctions. “When they sent in the package, and we initially opened it, our reaction was, ‘Oh my God! These are the nicest condition examples of this series that we’ve ever seen.’”

The cards were given away as a candy promotion around 1910. They include such baseball luminaries as Ty Cobb, Cy Young and Christy Mathewson.

Kissner assumes that his immigrant grandfather didn’t know what to do with them so he put them in the attic, and forgot about them.

Today’s value? At least $3 million.

And the best bunch– 37 cards– will be sold at auction right here in Baltimore when the National Sports Collectors Convention is held in August at the Baltimore Convention Center.

“When they called us up and said, ‘Karl, this is one of the most significant finds of baseball cards ever,’ I was like, ‘No, it’s just baseball cards. No.’ In this particular series, in this particular card, in this condition — some of them are in mint condition — it just blows everyone away,” Kissner said.

The Kissner grandfather is survived by about 20 family members who will divide the windfall when the cards are auctioned off.

Thirty-seven of the 700 cards being auctioned in Baltimore are expected to fetch around $500,000.

The highest price ever paid for a single baseball card is $2.8 million for a 1909 Honus Wagner card sold at auction in 2007.