As one of Europe’s most important countries, it is not surprising that France has a wonderful national library, and that this institution has a growing online presence. The website of the Bibliothèque nationale de France found at www.bnf.fr (or www.bnf.fr/en for the English version) leads you to the catalogue and tells you how to access the library’s many collections, including antiquities and works published in Paris in the 16th century.
Gallica https://gallica.bnf.fr is the BNF’s vast digital library, free to all through the Internet. Intended for use by all readers, including the casually curious, students and academics, this site includes medieval manuscripts, illustrations from the natural sciences, maps and photographs.
It might not seem obvious how Gallica could assist with your family history research, but you just need to stretch your imagination. The Patrimoine équestre collection, for example, focuses on horses, which were part of our ancestors’ everyday lives. (See https://gallica.bnf.fr/html/und/sciences/patrimoine-equestre) And as France was once a colonial power with a presence from the Caribbean to Polynesia and Africa, the maps on this site could prove helpful if your ancestors were sailors or merchants. (See https://gallica.bnf.fr/html/und/cartes/les-ameriques-en-cartes)
Another aspect of Gallica is a bilingual site called la France en Amerique, or France in America, created in collaboration with the Library of Congress. (See https://gallica.bnf.fr/dossiers/html/dossiers/FranceAmerique/fr/default.htm) In addition, if you are looking for a biography of a French ancestor dating back to the 12th century, BNF Gallica is the place to go. I discovered this by chance.
I was searching online for Jean Allaire, a Quebec City merchant who arrived in New France in 1658. He was associated with François Perron (Péron), a leading merchant in La Rochelle and Québec City. Google took me to the Dictionnaire Allard, also known as the Dictionnaire de Dauphiné, on BnF Gallica. (See https://gallica.bnf.fr/ark:/12148/bpt6k39393d/f12.item.zoom)
A dictionnaire in France can be a source of biographies, at least in the more expensive versions. For most of the 44 ancient provinces of France prior to 1789-1799, Bnf Gallica has posted dictionaries of important residents.
This particular dictionary addresses the ancient province of the Dauphiné. At the time of the French Revolution, Dauphiné was divided into three modern-day Départements: Drôme, Hautes-Alpes and Isère. According to Fichier Origine (/www.fichierorigine.com), 26 pioneers from Drôme, 27 settlers from the Hautes-Alpes and 70 pioneers from the Isère settled in Nouvelle-France.
Similar regional dictionaries covering other parts of France can be found on Gallica, and in them you may find information about your very distant French ancestors in France. For example, I discovered that my family name, which was Gagné in New France, was Gasnier in France in the 16th and 17th centuries, and it appears to have been Garnier in the 14th and 15th centuries. This is information I obtained through BnF Gallica and other free online research tools.