The Loire is the longest river in France. With a length of , it drains an area of , which represents more than a fifth of France's land area. It is the 170th longest river in the world. It rises in the Cévennes in the département of Ardèche at near Mont Gerbier de Jonc, and flows for over north through Nevers to Orléans, then west through Tours and Nantes until it reaches the Bay of Biscay at St Nazaire. Its main tributaries include the Maine, Nièvre and the Erdre rivers on its right bank, and the Allier, Cher, Indre, Vienne, and the Sèvre Nantaise rivers from the left bank. The Loire gives its name to six départements: Loire, Haute-Loire, Loire-Atlantique, Indre-et-Loire, Maine-et-Loire, and Saône-et-Loire. The central part of the Loire Valley was added to the World Heritage Sites list of UNESCO on December 2, 2000. The banks are characterized by vineyards and chateaux in the Loire Valley.
Historicity of the Loire River valley begins with the earliest Middle Palaeolithic period 40–90 ka (thousand years ago), followed by the modern humans (30 ka), succeeded by the Neolithic period (6,000 to 4,500 BC) of the Stone Age and the Gauls, the inhabitants in the Loire during the Iron Age, in the period between 1500 and 500 BC. Gauls made it a major naval trading route by 600 BC, establishing trade with the Greeks on the Mediterranean coast. Gallic rule ended in the valley in 56 BC with Julius Caesar winning over this territory. Christianity made entry into this valley from 3rd century AD with many saints converting the pagans. It was the time when the wineries also came to be established in the valley.
The Loire Valley has been called the "Garden of France" and is studded with over a thousand chateaux, each with distinct architectural embellishments covering a wide range of variations, from the early medieval to the late Renaissance periods. They were originally created as feudal strongholds, over centuries past, in the strategic divide between southern and northern France; now many are privately owned.
Studies of the palaeogeography of the region suggest that in the pathogeolic the palaeo-Loire continued its northward flow and joined the Seine, while the lower Loire found its source upstream of Orléans in the region of Gien, flowing westward along the present course. At a certain point during the long history of uplift in the Paris Basin, the lower, Atlantic Loire captured the "palaeo-Loire" or Loire séquanaise ("Loire-Seine"), producing the present river. The former bed of the Loire séquanaise is occupied by the Loing.
The Loire Valley has been inhabited since the Middle Palaeolithic period from 40–90 ka. Neanderthal man made boats out of tree trunks and stone tools and navigated the river. Modern man inhabited the Loire valley around 30 ka. By around 5000 to 4000 BC they began clearing forests along the river edges and cultivating the lands and rearing livestock. They built megaliths to worship the dead, especially from around 3500 BC. The Gauls arrived in the valley between 1500 and 500 BC and the Carnutes settled in Cenabum in what is now Orléans and built a bridge over the river. By 600 BC the Loire had already become a very important trading route between the Celts and the Greeks and would become one of the great highways of France for over 2000 years. The Phoenicians and Greeks had used pack horses to transport goods from Lyon to the Loire to get from the Mediterranean basin to the Atlantic coast.
Ancient Rome and the Vikings
During the Roman period, they successfully subdued the Gauls in 52 BC and began developing Cenabum which they named Aurelianis and also began building the city of Caesarodunum, now Tours, from AD 1. The Romans used the Loire as far as Roanne, only around from the source. After AD 16, the Loire river valley became part of the Roman province of Aquitania, with its capital at Avaricum. From the 3rd century, Christianity spread through the river basin and many religious figures began cultivating vineyards along the river banks. In the 5th century, the Roman Empire declined and the Franks and the Alemanni came to the area from the east. Following this there was ongoing belligerence between the Franks and the Visigoths. In the 9th century, the Vikings began invading the west coast of France and used long ships to navigate the Loire. In 853 they ruined Tours and its famous abbey, later ruining Angers in 854 and 872. In 877 Charles the Bald died, marking an end to the Carolingian dynasty. After considerable conflict in the region, in 898 Foulques le Roux of Anjou gained power.
During the Hundred Years' War from 1337 to 1453, the Loire River marked the border between the French and the English. One-third of the inhabitants died from the Black Death of 1348–9. The English defeated the French in 1356 and Aquitaine became English in 1360. In 1429, Joan of Arc persuaded Charles VII to banish the English from the country. Her successful relief of the siege of Orléans, on the Loire, was the turning point of the war. In 1477, the first printing press in France was established in Angers, and around this time the Chateau de Langeais was built. During the reign of François I from 1515 to 1547, the Italian Renaissance had a profound impact upon the region, and became deeply ingrained in the architecture and culture of the region, particularly among the elite and their chateaus. In the 1530s, the Reformation ideas reached the Loire valley and in 1560 Catholics drowned several hundred Protestants in the river. During the Wars of Religion from 1562 to 1598, Orléans served as a prominent stronghold for the Huguenots but in 1568 Orléans Cathedral was blown up by the Protestants. In 1572 the St. Bartholomew's Day massacre saw some 3000 Huguenots slaughtered in Paris, followed by the drowning of hundreds of them by the Catholics in the Loire River.
For centuries attempts were made to keep a navigable channel open by the use of wooden embankments and dredging. River traffic increased gradually, with a toll system being used in medieval times. Today some of these toll bridges still remain, dated to over 800 years. During the 17th century, Jean-Baptiste Colbert instituted stone retaining walls and quays from Roanne to Nantes which helped make the river more reliable, but navigation was frequently stopped by flood and drought. In 1707, floods were said to have drowned 50,000 people, with the water rising more than in two hours in Orléans. A typical passenger timetable from Orléans to Nantes took eight days, with the upstream journey against the flow taking fourteen.
Steam-driven passenger boats appeared soon after the beginning of the 19th century plying the river between Nantes and Orléans; by 1843, 70,000 passengers were being carried annually in the Lower Loire and 37,000 in the Upper Loire. However with the introduction of the railway in the 1840s trade on the river steadily declined and proposals to build a fully navigable river up to Briare came to nothing. The opening of the Canal latéral à la Loire in 1838 enabled navigation between Digoin and Briare to continue, but the river level crossing at Briare remained a problem until the construction of the Briare aqueduct in 1896, which at 662.69 metres was the longest such structure in the world for quite some time.
The Canal de Roanne à Digoin was also opened in 1838 and was nearly closed in 1971 but still provides navigation further up the Loire valley to Digoin. However the Canal de Berry, a narrow canal with locks only wide, which was opened in 1820s and connected the Canal latéral à la Loire at Marseilles-lès-Aubigny to the Cher River at Noyers and back into the Loire near Tours, was closed in 1955. Today the river is only officially navigable as far as Bouchemaine, where the Maine joins it near Angers, together with a short stretch much further upstream at Decize, where a river level crossing from the Canal latéral à la Loire connects to the Canal du Nivernais.
The monarchy of France ruled in the Loire Valley for several centuries and as a result it got the title "The Valley of Kings". Starting with the Gauls, followed by the Romans, then the Frankish Dynasty who were succeeded by the kings of France who ruled from late 14th century till the French Revolution and all of rulers were responsible for the development of the valley. The chronology of the rulers is presented in the table below.