It is the longest river in France--it has its source in springs on the mountain sides of the southern Cevennes hills within the department of the Ardeche. It flows north to Orleans, west through Tours and on to the Atlantic coast at Nantes.-- over 1000km . It would have been so much easier to have headed south for the Mediterranean!
Over such a distance it leaves its mark and valleys over a huge geographical area. The area commonly referred to as the 'Loire Valley 'or 'Val de Loire ' -- is the area along the river that takes in the majority of the famous chateaux -- and became formalised with its inclusion on the list of world heritage sites in November 2000. This was identified as the area along the river Loire between Sully-sur-Loire in Loiret and Chalonnes-sur-Loire in Maine-et -Loire (Anjou) a distance of 280km. It also takes in the Loire-Anjou-Touraine Regional Natural Park and the park at chateau Chambord.
So the 'Loire Valley' as far as UNESCO is concerned takes in the departments of Loiret, Loir-et-Cher,Indre-et-Loire (formerly Touraine) in the Centre region plus the department of Maine-et-Loire (formerly Anjou) in the Pays de la Loire region.
The Loire river gives its name to a number of departments of France as it flows towards the Atlantic: Loire (no connection with Val de Loire), Haute-Loire, Loire-Atlantique, Indre-et-Loire, Maine-et-Loire, and Saône-et-Loire.