It was not intended for war - its top sides are bound to two intake towers by a series of bridges. No doubt snipers nest there. On the far side of the dam, a small building provides access to the power plant below. That is where Oliver hides.”— Legate Lanius
Located at Hoover Dam, there are four intake towers in total. Two are located on the New California Republic (NCR) side of the Hoover Dam checkpoint, and the other two are on the Caesar's Legion side of the checkpoint.
The Hoover Dam intake towers appear only in Fallout: New Vegas.