Water inlet tower at Montferrand

The water entry tower, located at the highest point of Montferrand, controlled the arrival of the diverted Tiretaine stream. This ingenious system fed mills and workshops, guaranteeing flour and resources in spite of sieges.
The Entrée de l'Eau tower was not the most imposing, but it was undoubtedly the most strategic in the medieval town. Originally, the butte de Montferrand was surrounded by two streams flowing from the Tiretaine. In the 13th century, Montferranders diverted the northern stream to force it to enter the town at the highest point, beneath the water entry tower. The stream ran through the sloping quarters, using the water as a driving force to turn the mill wheels and grindstones. At the lowest point, near today's Roger-Quilliot art museum, was the water outlet tower.

The two northern districts of the medieval town were thus named: Moulins and Molles (millstones). This ingenious device ensured that the inhabitants continued to receive flour, even in the event of siege, and thus avoided famine.
The water circuit followed the rue du Puy Martel or Puits Martel, from the Occitan martelia: water valve, recalling the diversion of the Tiretaine upstream from the present-day Cataroux mill.
Part of the stream was also used by butchers and tanners in the lower parts of the Molles district. The foul-smelling stream produced by these activities was discharged beneath the destroyed Saut de l'Eau tower.

The Square du Moulin and its contemporary fountains are a reminder of the vital importance of the medieval system.