is considered temperate oceanic (Trewartha: Do) in the Trewartha climate classification. The city experiences cool to very cold winters, hot summers and relatively dry conditions throughout the year. Main sights Prehistoric Saint-Martin-de-Corléans Megalithic Area with artifacts and tombs dating to the Neolithic era. Ancient remains The ancient town walls of Augusta Prætoria Salassorum are still preserved almost in their entirety, enclosing a rectangle . They are high, built of concrete faced with small blocks of stone. At the bottom, the walls are nearly thick, and at the top . 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 square, and project 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 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. The east and south gates exist intact. The latter, a double gate with three arches flanked by two towers known as the Porta Praetoria (1st century AD) was the eastern gate to the city, and has preserved its original forms apart from the marble covering. It is formed by two series of arches enclosing a small square. The rectangular arrangement of the streets is modeled on a Roman plan dividing the town into 64 blocks (insulae). The main road, about wide, divides the city into two equal halves, running from east to west. This arrangement makes it clear that guarding the road was the main raison d'être of the city. The Roman theatre, of which the southern façade remains today, is tall. The structure, dating from the late reign of Augustus, occupied an area of ; it could contain up to 4,000 spectators. In the nearby was the amphitheatre, built under Claudius. A marketplace surrounded by storehouses on three sides with a temple in the centre with two on the open (south) side, as well as a thermae, have also been