To reach the Fort, the Courier must use the barge at Cottonwood Cove. However, it can not be taken until certain events take place in game. The Courier must either be invited when exiting The Tops after completing Ring-a-Ding-Ding!, Vulpes Inculta (or Alerio, if they have already killed Vulpes, who will comment on this) will be waiting outside, or if you have progressed in For the Republic, Part 2 to the part where you report to Colonel Moore that you have dealt with the Great Khans. If you have not yet been invited, the guards at the Fort may be hostile. If the Courier travels to Cottonwood Cove with Boone, Boone will immediately attack all legionaries on sight, causing them to turn on the player character. (unless you are wearing a Legion disguise.)
On either side of the entrance are sleeping tents. To the north of the entrance past the tents is a small bar. In the center of the camp are the Arena and Caesar's Tent. To the Southwest, there are more tents, another bar, and the weather monitoring station, which includes Mr. House's secret bunker. Standing on top of the hill near the entrance will let you see several other tents and structures off in the distance that you are not allowed to visit.
The Legion Arena is a small pit made of walls of scrap metal put together to form a post-apocalyptic Colosseum. Here the Courier, if male, can fight slaves to the death for the amusement of Caesar's legionaries. Females will be told they are not allowed to fight in the arena and will not have this option. The only exception is when you choose to kill Benny (if you haven't already dealt with him at The Tops) by fighting him in the arena, as a part of the quest Render Unto Caesar.
When arriving at the fort, towards the northeast there is a trench. Continuing along this trench until you reach the end, you will find a 500 bulk 5.56mm round.
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 DT by 10.
The location is actually far larger than the area that can be accessed by the player. From various locations throughout the camp you can see that the tents of the Legion stretch out far across the land surrounding the camp, though the gates to these areas are marked as "Inaccessible".
If you sneak to kill the guard at the gate (the one who confiscates your weapons), your weapons will not be confiscated on subsequent visits.
Lupa's dead body will remain in the arena unless you remove her brain.
Blood spurts out of the training dummies when you attack them with a power fist.
xbox360 If Vulpes Inculta is killed after the mark is given, and then becoming vilified by the Legion before traveling to The Fort the first time, going there will result in random resets of the reputations with other factions in the game (at least on the map).[verified]
xbox360ps3pc You may not regain all your weapons upon leaving the Fort, so make sure you save before you attempt to leave.[verified]
pc After leaving Caesar's tent, Cursor Lucullus may have completely disappeared, making it impossible to leave the fort or retrieve your equipment.[verified]
This can be fixed on PC by simply using "Prid [Ref ID]" and then "Moveto player"
xbox360ps3 Sometimes, if you have Boone waiting outside Fortification Hill, the guard outside Caesar's tent, the dog near him and everybody inside Caesar's tent except Caesar himself will be hostile. To prevent this, you must have previously kicked Boone from your party.[verified]
xbox360 If you leave the Fort after having the platinum chip returned to you by Caesar, the guard will take the chip. If you return to the Lucky 38 and kill Mr. House (not sure if it matters, but the demonstration of the securitron upgrades had not be initiated), the platinum chip will be added back to your inventory. Fast traveling back to the fort will initiate the same dialogue as trying to leave with the platinum chip. Choose the option to stay and they will not confiscate any of your items, leaving you fully equipped.[verified]
ps3 Sometimes you will be randomly killed by the guards when you walk up to the tent.[verified]
xbox360 Sometimes the Praetorian Guards in Caesar's tent will randomly attack even if you have the Mark of Caesar.[verified]
xbox360 When you try to leave the Fort by clicking on the gate, it will not trigger Cursor Lucullus to ask you if you are ready to leave.[verified]
xbox360ps3 After following Benny to the Fort and choosing the option to crucify him, upon returning to the drawbridge it is possible to see two Bennys one on the cross and another standing by it, the one standing by it can be talked to and untied, if you untie him you gain good Karma.[verified]
xbox360ps3pc There are a great many problems with corpses in the Fort. Any Ash Piles left in the Fort will respawn their inventories upon returning, as will some Non-Ash Pile corpses. Any normally killed soldiers may also spawn alive upon returning. Non-Ash Pile corpses also have a habit of vanishing not long after you've killed them, even if you don't leave the area.[verified]
pc When exiting the Fort with a companion, unique weapons that where confiscated may be duplicated in the companions inventory.[verified]
ps3 Occasionally, if you have a weapon drawn when you fast travel to the fort and you disarm when asked by the guard, your hands will remain in the position that they would be in for the weapon you had drawn, even though the weapon is absent. This can be fixed by pressing the reload button, which will bring up your fists. The conditions and specifics for this glitch are unknown.[verified]
xbox360ps3pc Sometimes upon entering the fort after wiping them out, a powder ganger will appear at the draw bridge. He will be hostile and wll be wearing simple powder ganger armor with a stormchaser hat.[verified]
xbox360ps3 If you kill everyone in the fort (not counting slaves or children) every time you re-enter, the dead bodies will respawn, dead, in the same spot you killed them but with new items on their inventories.[verified]
ps3 The area in and around the Fort may be extremely choppy when you first arrive there.[verified]
xbox360pc You can drop any weapons or chems you don't want confiscated if you bring up your [Pip-Boy as soon as the area is loaded. The guard will confiscate your equipment after you close your Pip-Boy. Then you can pick up the gear you dropped and use it in the fort.[verified]
pcps3 It is possible to fast travel with the platinum chip in your inventory by defeating Lupa in the arena during the Rex companion quest. [verified]
pc Pickpocketing the key to the gun lockers and then opening it turns the legionaries hostile.[verification overdue]