The United States has returned to Italy a rare copy of a letter Christopher Columbus wrote in 1493 describing his discovery of the Americas, after the document was stolen more than 25 years ago and replaced with a forgery.

Police said the genuine copy, worth €1 million ($1.13 million), had been stolen from a library in Florence and replaced with a phoney reproduction. The stolen document eventually ended up in the Library of Congress in Washington.

Columbus, an Italian explorer whose voyage across the Atlantic in 1492 relied on the then-unproven theory that the world was round, wrote the original letter to his financial backers, Spain's King Ferdinand and Queen Isabella.