How big is the world’s smallest book? And which novel has been read the most? For UNESCO’s World Book Day on April 23, we take a look at some quirky and impressive literary achievements.Nowadays, books are increasingly read on screens rather than paper. But for centuries, they have not only served as a means of communication, but have also been status symbols, works of art and collector items.

To promote the written word, UNESCO initiated World Book Day in 1995. Its date, April 23, goes back to a Spanish tradition. On the name day of Saint George, roses and books are given as presents in Catalonia.

April 23 is also the day William Shakespeare and Miguel de Cervantes, two of the most significant writers in the world, passed away.

To celebrate World Book Day, click though the gallery above for some astonishing record-breaking books.