With baseball season right around the bend, many people are beginning to get excited about the upcoming season. Along with this, collectors all over the globe are hoping to add valuable items to their collection.

In the United States, baseball is one of the most popular sports. After all, it is known as “America’s favorite pastime” for a reason. While some people enjoy playing the game and/or watching their favorite team on television, others have taken this one step further by collecting memorabilia.

From local estate sales to online auctions, there are many places you can visit to grow your collection. Here are five of the most expensive pieces of baseball memorabilia ever sold:

1. Mark McGwire’s 70th-home-run baseball. $3 million in 1999. When McGwire was chasing the homerun record during the 1999 season, it captivated the entire world. This ball is a piece of history, and the sales price shows it.

3. Babe Ruth bat used to hit first home run at Yankee Stadium. $1.265 million. Once again, Ruth memorabilia finds itself on the list. This bat was used by Ruth to belt the first home run at Yankee Stadium in 1923.

4. Babe Ruth sale contract from 1920. $996,000. When the Red Sox agreed to sell the Babe to the Yankees for $100,000 they made one of the biggest blunders of all time. According to Beckett Media, this is the most money ever paid for a sports document.

5. Hank Aaron’s 755th home run ball. $650,000. At the time it was hit, few realized that it would be the final home run smacked by Aaron. While the ball may not have been worth much when hit in July 1976, it later sold for $650,000.

As a baseball fan, you know just how fun it can be to collect memorabilia. These five pieces are among the most expensive of all time. As you continue to scour estate sales, you never know what you are going to come across.