Flen is a locality and the seat of Flen Municipality, Södermanland County, Sweden with 6,229 inhabitants in 2010.Flen evolved as a railway junction and got the title of a city in 1949. Since 1971 it is the seat of the much larger Flen Municipality.Other things which made Flen famous is "Violen från Flen", a song written by Ulf Peder Olrog in the 1940s. The town also plays an important role in "Du ringde från Flen", 1992 dansband song by Grönwalls.