When one thinks of an inventive book, a nice cover or a cool pup-up book might be the go-to. This book was inventive way before any of those things were around or relevant, as it was and still is the only six-way book.
The National Library of Sweden has in their possession an ancient text that opens in six different ways to reveal six completely different books. While an e-reader can hold hundreds of books for you at one time this book is a physical copy and as many avid readers will tell you, you just can't beat physical.
The books each open up with a set of clasps but open up differently. They actual texts contained within this books are all devotional German writings that were made between 1550 and 1570.
Not on front page