Mark of Caesar

The Mark of Caesar is a miscellaneous item in Fallout: New Vegas.

Characteristics
Given to the player by Caesar's representative upon exiting The Tops Casino after completing Ring-a-Ding-Ding, the Mark of Caesar allows safe passage to Caesar's camp even if the player has a low reputation with Caesar's Legion.

Bugs
Caesar's Legion may still be hostile towards the player, even when carrying the Mark of Caesar. This could be because you have a companion (like Boone) who hates the Legion. I notice this stops once we stop traveling together. They will also be hostile if you are wearing another faction's clothing while wearing the Mark of caesar ie. NCR.Causing you to fail all of Caesars quests.