A beloved children's book that features one of Sesame Street's main characters is celebrating it's 45th anniversary!

Sesame Street announced the celebration of the fan-favorite book "The Monster at the End of This Book," featuring Grover!

The book was first published in 1971 and has sold more than 12 million copies globally, making it the best-selling trade book in Sesame Street's 47-year-history.

It's a timeless story, which Sesame Street fans have enjoyed and shared!

You can find an audio version of the book below: