It rises in the highlands of the southeastern quarter of the Massif Central in the Cévennes range (in the department of Ardèche) at 1,350 m (4,430 ft) near Mont Gerbier de Jonc; it flows north through Nevers to Orléans, then west through Tours and Nantes until it reaches the Bay of Biscay (Atlantic Ocean) at Saint-Nazaire. Its main tributaries include the rivers Nièvre, Maine and the Erdre on its right bank, and the rivers Allier, Cher, Indre, Vienne, and the Sèvre Nantaise on the left bank.
The Loire gives its name to six departments: Loire, Haute-Loire, Loire-Atlantique, Indre-et-Loire, Maine-et-Loire, and Saône-et-Loire. The central part of the Loire Valley, located in the Centre-Val de Loire region, was added to the World Heritage Sites list of UNESCO on December 2, 2000. Vineyards and châteaux are found along the banks of the river throughout this section.
The human history of the Loire river valley begins with the Middle Palaeolithic period of 90–40 kya (thousand years ago), followed by modern humans (about 30 kya), succeeded by the Neolithic period (6,000 to 4,500 BC), all of the recent Stone Age in Europe. Then came the Gauls, the historical tribes in the Loire during the Iron Age period 1500 to 500 BC; they used the Loire as a major riverine trading route by 600 BC, establishing trade with the Greeks on the Mediterranean coast. Gallic rule ended in the valley in 56 BC when Julius Caesar conquered the adjacent provinces for Rome. Christianity was introduced into this valley from the 3rd century AD, as missionaries (many later recognized as saints), converted the pagans. In this period, settlers established vineyards and began producing wines.
The Loire Valley has been called the "Garden of France" and is studded with over a thousand châteaux, 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.
The name "Loire" comes from Latin Liger, which is itself a transcription of the native Gaulish (Celtic) name of the river. The Gaulish name comes from the Gaulish word liga, which means "silt, sediment, deposit, alluvium", a word that gave French lie, as in sur lie, which in turn gave English lees.