These are not postcards, but black-and-white photographic views mounted on cardboard in a postcard format. They were published by Fernand Nathan, a renowned publisher of school textbooks, around 1920.
The back of these cards, in light beige or very pale sea green, is blank with no inscriptions. They were intended as educational materials for primary schools.

Fernand Nathan was born in Passy (now part of Paris) in 1858. He began his career working for Charles Delagrave, a Parisian publisher and bookseller.
On June 8, 1881, at just 23 years old, he partnered with Jean-Baptiste Fauvé (1834–1893) to establish the "Librairie Classique Nicolas Fauvé et Fernand Nathan", located at 18 Rue de Condé in Paris’s 6th arrondissement. In 1884, Nathan bought out his partner’s shares, becoming the sole owner of the publishing house.
The company’s focus on educational publishing came at an opportune time: the Jules Ferry laws and educational reforms of the early decades of the Third Republic created a highly favorable environment for this sector, providing Fernand Nathan with significant opportunities.