Frederikssund is a Danish town located in the Region Hovedstaden. It serves as the seat of the Frederikssund Municipality and has a population of 17,639. The town was officially granted market town status in 1810.
The town is notable for hosting annual Viking Games and for housing the J.F. Willumsen museum. Additionally, it has been connected to Hornsherred via the Kronprins Frederik Bridge since 1935.