ST. IGNACE, Mich. (AP) — History lovers have a chance to own pieces of the original Mackinac Bridge with parts of the bridge’s steel grating placed on auction.

Barrels that weigh about 470 pounds and contain around 140 pieces of grating are on sale until May 18 when the auction closes. The pieces range in size.

Dozens of bids have already been placed with prices reaching over $500 a barrel.

The Mackinac Bridge Authority says the Mighty Mac is the third-longest suspension bridge in North America.

The bridge connects Michigan’s two peninsulas over the Straits of Mackinac.