Hoover Dam tower
The three towers on Hoover Dam
Located at Hoover Dam, there are four towers in total. Two are located on the New California Republic (NCR) side of the Hoover Dam checkpoint building, and the other two reside on Caesar's Legion side of the checkpoint. Out of the four towers the two central towers have elevators leading down to the Hoover Dam offices, with the eastern one requiring a key. The far east tower has also collapsed and as such can not be entered.
Hoover Dam towers appear only in Fallout: New Vegas.