- Geography: Municipality of the urban area of Carcassonne built on a hill at the foot of the massif of Malepère, Alairac is a circular village, or circulade one thousand, part of the urban community of Carcassonne (CAC) (Carcassonne or chipboard) since 1 January 2010.
- Borders of Alairac: Arzens, Caux, Lavalette, Montreal, Montclar and Villarzel-du-Razes, Roullens.
- Geology, topography and hydrography: The village overlooks the plain where winds canal du Midi and the view extends over a limited panorama to the north by the Black Mountain to the east we find the city of Carcassonne and further south, Malepère massif, covered with oak woods, fields of wild boar and mushroom pickers.
- Climate: The village is in oceanic climate with a strong Mediterranean influence in this area dominates the oak (or auzina), favorable to growing vines. The summers are tempered, low harsh winters.
- History:
- The first writings appear on the castle in 1063, construction of the probable circulade. It is then up to the Count of Foix, Roger I of Foix. Over the years, he exchanged several times between the county of Foix and the Viscount of Carcassonne, the Trencavel family.
- From the eleventh century, the village is crossed by one of the ways of Saint Jacques de Compostela said "way Pyrenean foothills", the pilgrimage continued until the eighteenth century.
- During the Albigensian Crusade, around Easter 1210, Simon de Montfort besieged the castle of Alairac for eleven days after which the inhabitants, fearing forced to surrender, fled by night. In 1309, the last known Cathar perfect, Guillaume Bélibaste, fled in Catalonia in the company of Philippe d'Alayrac. The latter, on his return to the country after ten years of exile, was probably taken and burned.
- On the sound of the approaching major Rover company, in 1366, the officers of the Seneschal of Carcassonne ordered the inhabitants of the castle of Alairac, which belonged to Jean d'Armagnac, to strengthen themselves and destroy the suburbs. Having failed to carry out this order, the Vicomte angrily set fire to the castle that was burned. Later, the Count of Armagnac Alairac gave the land of the Marquis de Mirepoix (1404).
- The lordship was sold at the beginning of the eighteenth century, a bourgeois of Carcassonne. This lordship is off to the Revolution in 1789.
- During the Great War 1914-1918, the village lost nineteen of the people whose names are inscribed on the memorial. Every year on November 11, this sacrifice is remembered by reading their names at a ceremony to which are associated schoolchildren.
- During the war in Algeria, several young people were called to fight Alairac. One of them is killed. All 19 March, a wreath laying takes place to commemorate the date of the entry into force of the Evian agreements.
- Alairac: His blazon is gold, a pal Comet Vert. "Golden" means that the coat of arms of the background is yellow. The "pal" in heraldry is an honorable piece placed vertically in the middle of the shield and bounded by two lines, "comet": colorful. "Sinople" refers to the color green.