The First Folio is a collection of 23 plays by William Shakespeare, including The Tempest, Much Ado About Nothing, and Romeo and Juliet. It was first published under the original title Mr. William Shakespeare’s Comedies, Histories, & Tragedies. It is credited with ensuring that his plays continue to be performed today. It was first published in 1623, seven years after the famous playwright passed away. Shakespeare’s plays might have been lost forever if not for it. First Folio was auctioned off in 2006 at Sotheby’s in New York for $5.2 million (roughly $6.3 million today). You could make a lot of money if any of these things are collecting dust in your attic.