If you've got a love for American iron on two wheels and about $15-$20 million burning a hole in your pocket, Mecum has an auction coming soon that you need to attend. The auction house is presenting what may be the best and most complete collection of rare vintage American bikes ever assembled anywhere.

They're auctioning off the , which includes about 220 motorcycles spanning almost 90 years. The stars of the show include Harley-Davidsons, Indians, Crockers, Merkels, Excelsiors and other makes from the 1910s and 1920s. The collection goes up to the early 90s as well.

It's the single largest assortment of American-built motorcycles ever offered to the public from one person's collection, Mecum says. The entire collection as a whole could fetch up to $20 million. It's already being called "The Antique Motorcycle Auction of the Century."

Here are some of the highlights from Mecum:

There are several bikes that will headline the offering including two of Cole's personal favorites, his 1907 Harley-Davidson Strap Tank and his 1910 Flying Merkel Twin Racer, both in original and unrestored condition. Other headliners, to name just a few, include Cole's 1915 Cyclone Board Track Racer formerly owned by Steve McQueen, his 1907 Indian Single, 1942 Crocker Twin and his 1912 Minneapolis Single.

They're almost entirely American, though a snuck in there somehow, but that's okay because those are cool. Some of these bikes have never been displayed publicly before.

The auction happens March 20 and March 21 in Las Vegas. here if you want to fill your morning with vintage motorcycle porn.