An 88-year-old poster featuring Babe Ruth, found hidden behind a wall during the demolition of a Minnesota home, is up for sale and could fetch more than $20,000.

The 14-by-22-inch poster, which oddly has the Bambino's first and last names reversed, was part of a promotion of a rare appearance by the legendary slugger in St. Paul, a town that did not have a Major League team in 1926. But the Yankees had used a day off to schedule a June 16 exhibition game against the St. Paul Saints, a minor league team that played in the American Association. Although the game was rained out, fans are said to have been treated to a batting practice demonstration featuring the Sultan of Swat's patented moonshots over the outfield fences of Lexington Park.

A discovery like the medium weight cardstock poster featuring baseball's most revered legend is enough to get collectors swinging for the fences, said Chris Ivy, of Texas-based Heritage Auctions, which is handling the sale.

“He’s the gold standard when it comes to sports collectibles,” Ivy said of Ruth. “Baseball collectibles comprise about 75 percent of the entire sports memorabilia market and the Yankees make up half of that. And the Babe is involved in the majority of Yankees’ collectibles; he’s the first sports icon that Americans really followed and looked up to.”

"He’s the gold standard when it comes to sports collectibles."

— Chris Ivy, Heritage Auctions

The game was scheduled during a Yankees' road trip to the Midwest, on a day off between games against the St. Louis Browns and the Chicago White Sox. Ruth, then 31, was having one of his best seasons, later finishing with a league-leading 47 home runs, 153 RBIs and a .372 batting average. After capturing the American League pennant, Ruth and the Yankees would lose the World Series in seven games to the St. Louis Cardinals.

Unlike baseball cards, which can become more valuable if they contain errors, Ivy said the poster’s imperfections — including a handwritten “1926” beneath Ruth’s legs — likely won’t boost its asking price.

“Our estimate is $20,000-plus, we’re expecting it to be in that range,” Ivy said. “It’s the only known poster to survive this barnstorming excursion. This is one-of-a-kind.”

The seller, Ivy said, miraculously stumbled upon the find during demolition of a home in St. Paul.

“As the walls were being knocked down, he noticed it within the paper insulation,” Ivy told FoxNews.com. “We let him know that he found a diamond in the rough, so to speak.”

Ruth would no doubt be amazed at the value of a poster bearing his likeness some 66 years after his death. But even in 1926, he would've been able to get in on the bidding: His salary was a then-astronomical $52,000.