Ouvrage Saint Ours Bas is a lesser work (petit ouvrage) of the Maginot Line's Alpine extension, the Alpine Line. The ouvrage consists of one infantry block. The location is unusual on lacking the underground galleries typical of a Maginot fortification, making it more like a blockhouse than an ouvrage. It was armed with two machine gun cloches and three heavy twin machine guns and six light machine gun embrasures. The interior is laid out on two levels. Construction began in July 1931, and cost 4.2 million francs to complete. The position controlled movement along RN 100.