The evolution of St-Calais can be seen in the urban development that took place in the Middle Ages, on either side of the river Anille. On the right-hand side, the former abbey site founded in the 6th century can still be seen in the two high gables of the current resource centre. After the French Revolution, it was replaced by an administrative centre with imposing buildings and straight streets typical of the 19th century. On the left-hand slope, on the hillside between the river and the castle founded in the 11th century to counter the powerful abbey, you can easily make out the medieval quarter created from the axis of the Grande Rue on an irregular and dense plot of land.