Caesar's Legion uses two old forms of currency which were also used in Roman times. They are minted by the Legion in the form of silver and gold coins, each coin bearing the profile of Caesar. Despite Caesar's poor relations with the other factions in New Vegas, Legion currency is still accepted as payment in the Mojave Wasteland, owing to the high level of trade with the Legion and the safety of its territory for caravans. The exchange rate is 4 bottle caps to 1 Denarius, and 100 bottle caps to 1 Aureus.
The Aureus (gold), which bears the portrait of the older Caesar on one side and the symbol of the 10th Legion (the bull) on the other. The inscriptions are in Latin, "Aeternit Imperi" meaning "For the eternity of the empire" on the front and "Pax Per Bellum" meaning "Peace through War" on the back.
A non-currency item versions of Legion Aureus exist within the game files of Fallout: New Vegas, but were not included in the final game. These versions are identical to the standard currency, but their trade value is affected by the player's Barter skill.
The Legion Aureus is the most rare form of currency in the Mojave Wasteland, and can only be found in a limited number of locations. Caesar's Praetorian Guard typically carry 2 Aurei each. The currency can also be obtained by cashing out at least 100 caps worth of poker chips for Legion money at any Casino.
Some can also be found inside an average locked trunk in Bloodborne cave, however this trunk is behind a very hard locked gate. A key, however, can be found at a campfire with a couple of chairs surrounding, further into the cave. They can also be found on Legion Assassins if your reputation with the legion is low enough.
Dropping a stack of 33,000 or more Legion Aureus breaks the game's 16-bit (4-hex) string used to store a number of items. This results in a stack of -32,000 Legion Aureus which will disappear from the players inventory when picked up.
The Aureus is one of two forms of currency used by Caesar's Legion, the other being the Legion Denarius. Of the two, the Aureus is both the most valuable and the least commonly found.
As with any form of currency in Fallout: New Vegas, Legion Aureus is not affected by the player's Barter skill. The currency will always be valued at 100 caps, regardless of whether the player is buying or selling.
Like the Legion Denarius, it does not show up when the items are sorted into item type on the container menu. It only shows up when the items are sorted back alphabetically on the container menu.