Legend has it that Princess Carcas, wife of the Saracen, Balaak, seeing Chalamagne lift the siege of her town, ordered the bells to be rung.

From Wiki:

History says that Charlemagne’s army was at the gates of the city facing the Saracens. A princess was at the head of the Knights of the City after the death of her husband. This is Princess Carcas. The siege lasted five years.

But early in the sixth year, food and water were becoming increasingly rare. Lady Carcass would take inventory of all reserves remaining. The villagers brought him a pig and a sack of wheat. She then had the idea to feed the pig with the sack of wheat and then precipitate it from the highest tower of the City outside the ramparts.

Charlemagne and his men, believing that the city was full of food even to the point of wasting pigs fed with wheat, raised the siege. Seeing Charlemagne’s army to leave the plain before the city, Lady Carcas elated by the victory of her stratagem decided to ring all the bells of the city. One of the men of Charlemagne then exclaimed: “Carcas sonne!” (it mean’s “Carcas rings”). Hence the name of the City.

The top photo shows a replica of the the sculpture in the bottom photo and is situated at the Porte Narbonnaise entrance to Carcassonne.  The original sculpture can be seen inside the Counts Castle.