The Chains of Judecca are massive chains located within the Inferno, all created to keep Lucifer imprisoned in Lake Cocytus. All the Chains that Dante encounters are found each time he descends into a lower circle. Every time Dante finds one of these, he uses the Scythe to destroy it to continue his progress. However, each time a chain is broken, Lucifer's laugh is heard, indicating that he is slowly being freed.
The last piece of the chain found is after the last Beatrice Statue. Breaking this one leads to the fight with Lucifer himself.