Fortification Hill

 is a Caesar's Legion base where the slavers keep an eye on the Hoover Dam. This is also the location where the Platinum chip is used to install the upgrades to the Securitrons. The Fort is built above Mr. House's secret bunker (see second note) The Fort can be reached by taking the barge at Cottonwood Cove. The barge itself might appear at first to be just a part of the dock (you might not think anything's there). It's actually a flat 12x12 raft roped up alongside the dock. This barge can be used whether the Legion soldiers at the cove are friendly, enemies, or even dead. However, you can not take the barge until certain point of game (you can not click on it). You must either be invited (after killing Benny, Vulpes Inculta would be waiting outside The Tops casino with Mark of Caesar), or you have to progress For the Republic, Part 2 to the part where you report to Colonel Moore that you have dealt with the Great Khans. Afterward you get bunch of of Caesar-related quests failing notifications. If you have not yet been invited, the guards at the Fort may be hostile. If you travel to Cottonwood Cove with Boone, he will immediately attack all legionaries on sight, causing them to turn on you. This will happen even if you have been invited.

The Arena
Speak to Otho -who is standing to the right of the arena gate- in order to participate in arena matches. When you enter a contest (which will grow harder as you progress through the ranks) your weapons and equipment will be confiscated. There is an easy trick around this by simply dropping the desired weapons and ammo for them in the arena before the fight starts (the arena is open for access when there are no battles).

Battling in the arena will give you fame with Caesar's Legion, allowing you to become Idolized by fighting all opponents and doing only 1 additional quest (of your liking) that gives fame.

All arena opponents (as well as yourself) will be either unarmed or equiped with machettes. Read the trick above if you want to bring your own goodies.

If you are a woman character, Otho will say "Know your place woman... only men are allowed to fight in the arena," and you will not be allowed to fight.

Notable Loot

 * 2000 caps in the very hard locked footlocker in Caesar's room.
 * A displacer glove which Caesar is wearing.
 * Numerous Ballistic fist which many of his guards are wielding.
 * Lupa's Brain (used during Nothin' But a Hound Dog). You must kill Lupa for her brain. You may speak to Antony, who is standing beside her, to arrange an arena fight with Lupa.  Alternatively, you may attack Lupa where she stands, but it will turn everyone at the camp hostile.  Lupa's Brain increases Rex's health from 350 to 550.

Loot if Benny is Still Alive
 * Caesar's Armor
 * Benny's Suit, if you let him escape and you decide to kill him.
 * Maria, Benny's gun if you let him escape and you decide to kill him or pickpocket him.

Bugs

 * When you enter the fort, sometimes you will see excessive tearing of the screen everywhere.
 * Most companions will glitch between Cottonwood Cove and the Fort, thus making it impossible to go into Caesar's tent. This may be possible to solve by having your companions wait in Cottonwood before taking the barge.  Once there, fast travel back, have them follow you, then fast travel to the fort.
 * You may not regain all your weapons upon leaving the fort, so make sure you save before you attempt to leave. Confirmed.
 * Boone may not warn you prior to leaving Cottonwood Cove that he will murder everyone in sight once you reach The Fort.
 * Sometimes Cursor Lucullus may disappear making it impossible to leave the fort since fast travel isn't allowed.
 * If the player decides to slaughter everyone inside the Fort (the area where Caesar's Tent is), exiting and re-entering will cause the corpses' clothing to disappear and it will re-spawn all loot on the body infinitely, making it a great way to earn caps.
 * If you save before going in to the fort the file may become corrupted and cannot load again and if you die inside the fort and you load your save game in entering before the fort the game loading screen will freeze thus the game become corrupted
 * Upon entering, all items may be floating, including the Slave Ledger required to win Great Khan sympathy, so make sure to check the air.
 * If at any time you decide to fight in the arena, there seems to be a chance that your inventory will glitch after you win your fight, raising the weight you're carrying by anywhere from 80-100 pounds, even though you're not carrying anything new after you get all of your stuff back.

Appearances
appears in Fallout: New Vegas.