The five architectural photographers chosen by the French government for the mission héliographique to record ancient and medieval monuments suffering from centuries of damage and neglect, worked from a massive inventory drawn up by antiquarians and architects. Le Secq was assigned Champagne, Alsace and Lorraine, followed by Strasbourg, Amiens, Rheims and Chartres. Le Secq made a detailed and loving study of Amiens Cathedral, more than forty-five large-scale prints, which involved circling the building at different levels and photographing it from different angles.