"Radio Station" is a side quest available in Dying Light. This quest is offered by Savvy at the Embers' Tower. Kyle Crane has to enter a radio station though a door on the ground floor, kill all of Rais's Men who wield rifles inside, and leave through an elevator to the rooftop. Upon completion of this quest, the radio station will be unlocked as a safehouse for Kyle and a trader will also occupy the safehouse for the rest of the game.
Savvy told me about an outpost in the radio station taken by Rais's bandits. Paying them a visit may be a good idea.
- Clear the Radio Station Outpost