[2] A further foundation stone was laid at the northeast corner of the building in the presence of the young sons of Frederick II Eugene, Duke of Württemberg on 12 September 1776.

[4] The building was designed by Philippe de La Guêpière in the neoclassical style, built in dark sandstone from Vosges at a cost of 80,000 French livre,[5] and was officially opened in time for the council meeting on 13 November 1778.

The central section featured a short flight of steps leading up to three panelled doorways flanked by brackets supporting a balcony with fine iron railings.

At roof level, there was a small belfry: the bell was inscribed with the message "Ave Maria gracia plena Dominus tecum benedicta tu in mulieribus" ("Hail Mary, full of grace, may the Lord be with you, blessed are you among women").

[11][12] At the end of the First World War, a plaque was installed on the façade of the building inscribed with the words "Les Armées et leurs chefs, Le Gouvernement de la République, le Citoyen Georges Clemenceau, président du conseil, ministre de la guerre, le Maréchal Foch, généralissime des armées alliées, ont bien mérité de la patrie" ("The Armies and their leaders, The Government of the Republic, Citizen Georges Clemenceau, President of the Council, Minister of War, Marshal Foch, Generalissimo of the Allied Armies, deserve the praise of the fatherland").