The Greeks first tried to settle in Celtic Gaul and managed to establish a small colony in Marseille in 600 BC. Then it was the turn of the Romans, lead by Julius Caesar, who entirely invaded Gaul during the Gallic Wars (58-51 BC). The Romans brought unity and peace for two centuries of Pax Romana during which agriculture, cattle-breeding and urban development were greatly improved. 
France.com Blog
Middle Ages
Charles Martel, the first leader of the Carolingian dynasty, initiated the expansion of the Franks’ kingdom and stopped the Muslim advance from Spain in 732. Charlemagne (742-814) continued this expansion and conquered most of Germany and Italy to reunite most of the former Roman Empire. Shortly after his death, however, his kingdom was divided under the pressure of invaders such as the Normans (Vikings) and the Magyars (Hungarians). 
Romanesque Era
Romanesque – 10th to 11th century
After the collapse of the Roman Empire, Christianity brought a sort of unity and calm to France. As witnessed by the multitude of churches, religion was omnipresent during these turbulent times of Barbarian invasions. The churches of this era, inspired by Roman architecture (thus the name romanesque), are charaterized by round arches, barrel-vaulting and large walls, a simple but heavy style.
Renaissance
In the early 16th century, after a series of Italian wars, Francois I strengthened the French Crown and welcomed to France many Italian artists and designers such as Leonardo da Vinci. Their influence assured the success of the Renaissance style characterized by enlarged doors and windows, the great sophistications of the interiors. 
Introduction
Not large by North American standards (about the size of the state of Texas), France is nonetheless extremely diverse: it concentrates a wealth of scenery, regional identities each with their own particular joie de vivre defined by cultural and historic differences. 
Through the years, France’s stamp on western civilization has left an indelible mark in many domains and French savoir-faire remains a reference in the arts, politics, gastronomy, fashion and science.
Gothic Era
Gothic – 12th to 14th century
During the Middle Ages the fortress style of the romanesque buildings was refined and improved by French masons and architects.
Grand Siècle
The 17th century was marked by a period of exeptional power and glamour for the French Monarchy. Starting with King Louis XIII and the Cardinal Richelieu who together transformed the feudal French Monarchy to an Absolute Monarchy, by controlling the opposition of the “Grands” (the Lords) and the growing power of the Protestant (siege of La Rochelle, 1628). Mazarin, Louis XIV’s regent, ended the popular revolts of La Fronde.
Bastille Day
This month, like every year on the 14th of July, the French will celebrate their Fête Nationale or Bastille Day, as it is known in English-speaking countries. It commemorates the storming of a Paris royal fortress––the Bastille––on July 14, 1789, a date of great historical significance as it marks the transition from an absolute monarchy to a republican regime.
Revolution Era
The 18th century’s Enlightment brought thinkers such as Voltaire and Rousseau to struggle against the principles of the old regime and absolutism. In 1789, the state’s financial crisis brought social turmoil, triggering the Revolution. On July 14th, a Parisian mob revolted and stormed the Bastille prison, symbol of the old regime.
Social Customs
French society likes formality in many aspects of everyday life as obligatory handshaking or cheek kissing 
, the use of the vous (rather then the familiar tu) and of titles when refering to a superior or a stranger and the concern about always dressing well.