From Marcialla going down to Certaldo, before Tavolese you find on the left a panel for "Pogni" after a few chilometers you will find this ruining Tower.
There are so many historic treasure on this country that many of them are simply ruining because nobody has the time to preserve them. The tower of Pogni is one example.
From the hill where the tower stand you see on the hill on the other side the church of Nebbiano