The commune is located in theLauragais valley some 15 km west ofCarcassonne and 15 km east ofCastelnaudary. The route D6113 passes through the commune from west to east between these two cities and becomes National Route N113 near Carcassonne. The Autoroute des Deux Mers (A61, E80) passes just 1 km south of the commune but the nearest exit is to the D43 nearBram. Other roads running into the commune are the D8 fromMontolieu in the north, the D34 fromSaint-Martin-le-Vieil in the northwest, and the D33 running west to east from Bram toVillesèquelande forms the southern border of the commune with a connecting road running north to the village. TheBordeaux-Sète railway runs west to east across the southern part of the commune but there is no station. The nearest station is at Bram.[3]
TheFresquel river runs from west to east through the commune passing just south of the village and joining theAude at Carcassonne. The Fresquel is joined by theLampy just east of the village and a number of streams flow into the two rivers including theRuisseau de Fontorbe, theRuisseau de Rebenty, theRuisseau de Falgous, and theVernassonne which forms a part of the northern border of the commune. TheCanal du Midi also passes through the southern part of the commune.
The commune is mostly farmland with some forests in the north. Apart from the village of Alzonne there are also the hamlets of Fongayraud and La Rode near the village, and La Migance in the north.[3]
The nameAlsona dates from 898 and comes fromFresquel. It is based on theHydronymic rootalz- meaning "alder" or "swamp" (Dauzat, Negre, Billy, Morvan) and the suffix-onna.
Alzonne from the 9th century was a town of some importance as it was once the capital of theviguerie of its name:vicaria Ausonensis; therefore Alzonne was also knownin pago Carcassensi. In this respect the situation of Alzonne has hardly changed since this small town is today the capital of the canton of its name in the arrondissement ofCarcassonne.
Its ancient and enduring importance is due to the fertility of its land and the rivers that form its fertile valley. Once the city was fortified and was besieged and taken three times during theWars of Religion of the 16th century.[4] It was a strategic place in the crusade against theAlbigensians.