Aosta is the capital of the Valle d’Aosta region, in northwestern Italy. It's near ski resorts and the Gran Paradiso National Park, which has an alpine botanical garden, trails and wildlife like ibexes and eagles. Remnants of Aosta's Roman past include the Arch of Augustus and the Praetorian Gate, once the city’s main entrance. In the Sant'Orso complex are a Romanesque cloister and a priory with a frescoed chapel.

Aosta is the capital and largest city of the Aosta Valley, a bilingual region in the Alps, 110 km (68 mi) north-northwest of Turin in Italy. It is situated near the Italian entrance of the Mont Blanc Tunnel and the Great St Bernard Tunnel, at the confluence of the Buthier and the Dora Baltea, and at the junction of the Great and Little St Bernard Pass routes. It has 33,127 inhabitants.

Aosta was settled in proto-historic times and later became a centre of the Salassi, many of whom were killed or sold into slavery by the Romans in 25 BC. The campaign was led by Terentius Varro, who then founded the Roman colony of Augusta Praetoria Salassorum, housing 3,000 retired veterans. After 11 BC Aosta became the capital of the Alpes Graies province of the Empire. Its position at the confluence of two rivers, at the end of the Great and the Little St Bernard Pass, gave it considerable military importance, and its layout was that of a Roman military camp.

After the fall of the Western Empire, the city was conquered, in turn, by the Burgundians, the Ostrogoths, and the Byzantines. The Lombards, who had annexed it to their Italian kingdom, were expelled by the Frankish Empire under Pepin the Short. Under his son, Charlemagne, Aosta acquired importance as a post on the Via Francigena, leading from Aachen to Italy. After 888 AD it was part of the renewed Kingdom of Italy under Arduin of Ivrea and Berengar of Friuli.

In the 10th century Aosta became part of the Kingdom of Burgundy. After the fall of the latter in 1032, it became part of the lands of Count Humbert I of Savoy.

The privilege of holding the assembly of the states-general was granted to the inhabitants in 1189. An executive council was nominated from this body in 1536, and continued to exist until 1802. After the Congress of Vienna restored the rule of Savoy it was reconstituted and formally recognized by Charles Albert of Sardinia, at the birth of his grandson Prince Amedeo, who was created duke of Aosta.

The ancient town walls of Augusta Prætoria Salassorum are still preserved almost in their entirety, enclosing a rectangle 724 by 572 metres (2,375 by 1,877 ft). They are 6.4 metres (21 ft) high, built of concrete faced with small blocks of stone. At the bottom, the walls are nearly 2.75 metres (9.0 ft) thick, and at the top 1.83 metres (6.0 ft).

Towers stand at angles to the enceinte and others are positioned at intervals, with two at each of the four gates, making twenty towers in total. They are roughly 6.5 metres (21 ft) square, and project 4.3 metres (14 ft) from the wall. Of the 20 original towers, the following are well preserved:

• Tour du Lépreux (French for Leper's Tower), was given this name after a leper called Pierre-Bernard Guasco who was jailed there in the late 17th century. Le lépreux de la cité d'Aoste, a novel by Xavier de Maistre, is also named after this leper.
• Tourneuve (13th century).
• Tour du Pailleron.
• Tower (Castle) of Bramafan, built in the 11th century over a Roman bastion. It was the residence of the Savoy viscounts. In Franco-Provençal, Bramé la fan means "To scream for hunger".
• Tour du Baillage.
• Tour Fromage.