Alleen or Lyngdal is a town which is the administrative centre of the municipality of Lyngdal in Agder county, Norway. It lies along the east side of the river Lygna, just north of the head of the Rosfjorden and northeast of the head of the Lyngdalsfjorden. The small villages of Skomrak and Svenevik both lie just south of the town, and the small farming area of Hæåk lies about 8 kilometres (5.0 mi) to the northwest. On 1 January 2001, the municipal government declared the urban area of Alleen to be a town called Lyngdal. Both names are used to refer to the urban area. In Norway, Alleen is considered a by which can be translated as either a "town" or "city" in English.
Lyngdal Church lies in the northern part of the town. The European route E39 highway and County Road 43 both pass through the town. It previously had an annual cattle auction. Alleen is the site of the largest primary and secondary schools in Lyngdal. The 4.64-square-kilometre (1,150-acre) town has a population (2019) of 5,159 and a population density of 1,111 inhabitants per square kilometre (2,880/sq mi).