The chain tying up Pantagruel in his cradle
Smaller than Saint-Nicolas' tower, the Chain tower went to ruin when king of England, who used to be La Rochelle's master, decided to refit the old harbour of William of Aquitaine. He built up the tower in the 15th century.
A chain which used to be tighten between Saint-Nicolas' tower and the Chain tower, in order to forbid the harbour's access and get a right of way on goods.
Famous French writer Rabelais wrote that chain came in handy to tie up Pantagruel in his cradle... you can figure its size!