New Orleans is a major city on the southeastern coast of the United States that was built and founded by the Mikaelson Family many centuries ago. It is the location of one of the biggest and most diverse supernatural communities in The Vampire Diaries universe. The Mikaelson family was in control of the city until 1919, when they were all forced to flee town when they were found by their own father. In their absence, Marcel, Klaus' former protégé and surrogate son, took over, unbeknownst to the Mikaelsons, who were under the impression that Marcel died in the chaos of their father's presence.
In the modern day, Klaus returned to the city with the hope of taking over again and reuniting his family after learning that he had impregnated his lover Alexandria, a Tribrid which is revealed a loophole that Klaus, despite being a vampire, was able to have children and Alex being the first of her kind can have children too. However, the family's return had the effect of further aggravating the already major ongoing conflict between the witches, vampires, and werewolves of the city.
The conflict started less than a year prior to the Mikaelsons' return, when Marcel interrupted The Harvest, a sacrificial ritual that acted to strengthen the bond between the witches in New Orleans and the magical power of their dead ancestors, from whom they drew power. Marcel's intervention resulted in the deaths of the majority of the witches in attendance, including all but one of the coven's Elders.
The Vampires Diaries spin-off, The Originals, mainly follows the story of The Mikaelson Family as they struggle to regain control of the city that was once theirs and, in the process, face off against powerful enemies from their past while they attempt to form alliances with the various human and supernatural factions.