Fæstningskanalen (literally "The Fortification Canal") is a canal in central Kongens Lyngby, Lyngby-Taarbæk Municipality, Copenhagen, Denmark. Created in the 1880s as part of the new fortification ring around the Danish capital, it runs from Lyngby Lake in the west to in the east. From there it originally continued to Ermelunden in Jægersborg Dyrehave, but this last leg of the canal is no longer filled with water. The project also included a more upstream straightening of the section of Mølleåen that connects Furesø in the west to the west side of Lyngby Lake in the east. The canal complemented the West Rampart (Vestvolden) and a series of coastal fortresses which were built at the same time. In the event of an enemy invasion, a dam at each end of the canal, one at Frederiksdal and one at