The construction of a "curtain” (a small wall linking two towers) between the Tower of the Arcade and the Tower of Liberty is attested from 1441. The Tower of Denis was constructed against this curtain around 1479. It is also located near a postern (small door integrated into the wall) which was part of the first line of defense that operated during the 14th century. On a relief-map of the fortifications of Mont-Saint-Michel, dated to 1690 and conserved at the Invalides, the Tower of Denis appears to be partially ruined by the action of marine currents. Due to its poor state and its location on a section of the rampart that was already well protected by the Arcade and Liberty Towers, the engineer Pierre de Caux, in charge of the restoration of the fortifications, considered the possibility of its elimination. The Tower of Denis was then demolished in 1732 and the continuity of the rampart was thus restored.
In the near future, the remains of the Tower of Denis will be likely be at least partially restored by François Jeanneau, the head architect of the Historic Monuments department.
In 2005, an Inrap team recovered a large quantity of schist molds used to cast pilgrimage symbols (Scallop shells, the effigy of Saint-Michel, etc.) in the location of a production workshop dated to the 14-15th centuries, near the entrance to the Abbey. Due to their variety and quality, these pieces now serve as reference objects in Medieval archaeology.
