The present invention relates to a wind turbine tower comprising a tower vibration damper (100) with a tuned mass damper and one or more impact damping units (113, 114, 115, 200, 300, 400). The tuned mass damper comprises a pendulum structure (101, 208), a chamber connecting a friction media (112) to the pendulum structure (101, 208) is at least partly immersed, and a suspension arrangement (103-111) suspending the pendulum structure (101, 208) inside the wind turbine tower such that the pendulum structure (101) is allowed to displace from a neutral position towards the outer boundary (102) of the chamber. The impact damping units (113, 114, 115, 200, 300, 400) are positioned between the pendulum structure (101, 208) and the outer boundary (102), such that the outer boundary (102) of the chamber and the pendulum structure (101, 208) may collide via the impact damping units (113, 114, 115, 200, 300, 400).