What was the book where the clue was hidden in the back of a famous statue in Europe?

Signilda: What was the book where the clue was hidden in the back of a famous statue in Europe?
Someone wrote in Reader’s Digest that they read this intriguing book (maybe about spies) where the big clue was a note hidden in the neck of a famous statue. This person actually visited the statue and reached behind it and found a note which read “good book, wasn’t it”. I always wanted to know the name of that book and the name of the statue too.

Answers and Views:

Answer by angie
Wow, that sounds like a book I would enjoy. I will watch and see if anybody can tell you the name of it.

Answer by antigone
I’m not entirely certain, but would it be the book entitled A Treasure’s Trove?