After laying siege to Laon, Henri IV ordered the construction of the citadel in 1594, directed against the town itself as a reprisal.
The plain district was destroyed, along with the Notre-Dame-au-marché and Saint Georges churches. The work, directed by Antoine Etienne, was completed in 1598, the year in which the governor took possession.
At the end of the reign of Louis XIV, it was demilitarized and abandoned to the retreating military, and a redevelopment of its fortifications began under Louis-Philippe in the mid-19th century. *
During the First World War, the citadel was occupied by German troops and used as a cantonment camp and hospital.
It should be noted that the citadel is not open to visitors, unlike its underground passages, where the Secrets Under the City tour takes place daily!
(For practical details, please contact the Tourist Office).