Tomi Valny
Google
To my opinion this is a number one place to visit in Lucca. Its quite unique to see such a 45 m high tower made of brick and stone of local Romanesque-Gothic architecture with trees growing on its top. Just imagine, in the beginning of 14th century there was about 250 towers in Lucca!
And as for every tower, if you climb up 233 steps you'll be awarded by 360deg view of old city of Lucca and surrounding mountains. View is stunning, just keep in mind the upper platform is very small that you can barely surround it because of crowds. Entrance is from behind the tower, not on the main street. If you want to buy ticket on place you'll have to probably wait about 15 minutes till the new slot is released, as this place is the most visited in the city. To buy tickets online its very difficult as the website doesn't work properly.