Please note that this is the article on the magic transportation device used by the Noah family, if you are looking for the article on the story arc happening inside it then you should head to Noah's Ark Arc.
Noah's Ark (ノアの方舟, Noa no Hakobune) is an artifact created and used by the Noah Family. It takes the form of a large, airborne cube that contains a city inside of it, as well as countless doors that those who control the Ark can use to go to any location in the world. One Ark, the White Ark, is currently in the hands of the Black Order, while the other, the recently made Black Ark, is in the hands of the Noah Family. Maitora is the one who created the technology and magic that make the ark work.
The Ark's Origin
According to the account in Book of Genesis, there was a time when God looked down on the world and was sickened by how wicked humankind had become, and decided to drown the world in a Great Flood. He found, though, one man he felt was the most righteous man of that age and charged him with the duty of building an Ark to save his family and two of every animal on the planet. The flood came and went, and the Ark came to rest on Mount Ararat, where God then commanded Noah to go forth and replenish the world.
As things played out with the Earl of Millennium, though, seven thousand years ago Noah and his kin fought a great war with the wielders of Innocence that resulted in the death of the Earl and the destruction of the planet in a great flood, chronicled in the Cube as the "Three Days of Darkness". After the death of the Earl, and after the flood waters receded, the twelve remaining members of the Noah Family went forth and repopulated the planet, making Noah's bloodline the ancestor strain of all humans. Since its creation, Noah's Ark has belonged to the Noah Family, though after the Fourteenth damaged it thirty-five years ago, making it inoperable to all but Allen Walker, the current Earl made a new Ark while Allen stole the old one, which is now in service to the Black Order.
Specifically, the Noah Maitora, who represents the Noah Family's "Ability," is the one responsible for the technology that makes the Arks work.
The Change Between Arks
During his failed coup thirty-five years ago, Nea D. Campbell, the only person other than the Earl and Road Kamelot at the time who could control the Ark, damaged the control systems of the Old Ark, rendering it useless to the Noah Family and passing on his ability to control the Ark to a new person, Allen Walker.
With his position in Edo compromised by Cross Marian hunting him down for his Ark's Akuma Egg, the Earl ordered Road to begin construction of a new Ark, simultaneously entrapping Lenalee Lee, Allen Walker, Lavi, Chaozii Han, Yu Kanda and Arystar Krory III in the old and starting the old Ark's destruction sequence to wipe out Lenalee (who, at that time, was a viable candidate for being the Heart). Three hours later, the Earl began the final preparations, starting the creation of a new Ark, this one black, while the old ark, this one white, began to implode. Before he could finish, Allen intervened, resulting in the Earl's new Ark being incomplete, with 80% of the new Akuma Egg being lost. Allen then directed the new Ark back to the European Branch Headquarters, where the Black Order made the decision to use it to their advantage.
The Two Arks
There are now two Arks. The original Ark (the 'Old Ark (旧方舟, Kyū hakobune) belongs to the Black Order since Allen's use of it, as it became "faulty" because of Nea's interference. Although anyone in the Order can walk into it, only Allen can create Gates at will and step into the Ark wherever he wishes. The Gates he creates can be used by anyone else afterwards.
The second Ark (the New Ark (新方舟,, Shin hakobune) was created by the earl and Maitora after he downloaded the original Ark into the new form. This downloading was mostly the effort of Road, though the Earl played an organ instrumental to it new Ark's completion in the final stages. However, the download of the Akuma Egg suffered an incomplete, and lost 80% due to the interference of Allen. It seems that this ark can be used by other members of the Noah family besides the earl, Road and Nea.   
To be completed
Controlling The Ark
The original Ark could be controlled by the Earl, Road, and Nea, the fourteenth Noah. After he betrayed the Noah, though, Nea passed on his ability to control the Ark to Allen, also making it impossible for the Earl and Road to control it.
The Ark is now controlled using a song that only Allen, Nea and Nea's brother, Mana Walker, understand, Mana having taught Allen and the special, musical notes the tune is sung/played to. After practising, Allen discovered that he doesn't need the piano within Nea's special room to control the Ark; he can open new Ark Gates by reciting the lyrics of the song to himself, though he can only make Ark Gates to places he has been to. All Gates in the outside world are numbered, and walking through them leads one to the Mediterranean-style city within the Ark. From there, walking through another door that connects to an established Gate teleports the person walking through to wherever the Gate was opened at, no matter how far away it is from the previous Gate's location.
Access to the Gates from the outside world can be controlled by anyone using the corresponding doors within the Ark, with established Ark Gates capable of being activated and deactivated by opening and closing the corresponding door, respectively, within the Ark. Using this principle, the Order regulates the Gates and access to them by keeping the doors of Gates that are not in use closed, and by only opening the doors at certain times. Even when the Gates are deactivated, their location is marked by a series of concentric circles with a number in the center that marks it with the corresponding door within the Ark.
To prevent infiltration, the Order also assigns a specific number code to each person that they are to trace on the palm of the person guarding the Gate, and no one can be let through if they do not know their numerical code.
In addition to making Gates, Allen can also destroy Gates using the magic command "Arda."
After Allen escaped from confinement and from Apocryphos, he opened the Gate one more time to escape from the Black Order, and then claiming that he will not rely on the Ark again. Since then, the Order has continued to rely on the Ark to ease their increased workload, though they cannot create new Gates and can only rely on preexisting ones.
- In the Genesis in the Bible, Noah's Ark is the vessel built by Noah following the command of God which would allow him, his family and two representatives of each animal species to survive the great flood.
- An Ark, in its most basic sense is a vessel, an object that can contain things or people.
|The Noah||The Earl of Millennium • Road Kamelot • Tyki Mikk • Skinn Bolic • Jasdevi • Lulu Bell • Nea D. Campbell • Sheril Kamelot • Wisely • Toraido • Fiedla • Maushyma • Maitora • Allen Walker|
|Akuma||Mana Walker • Claire • Leo • Pierrot • Eliade • Eshi • Thread • Chomesuke • Lesley • Alma Karma • Mimi • Doug • Ice • Pang • Kazekiri • Sara • Doug • Sophia • Wizard Akuma • Rabbit Akuma • Level 3 (Paris) • Level 4 (Headquarters) • Level 4 (Paris)|
|Other||Dark Matter • Noah's Ark • Cell Roron • Lero • Teez • Akuma Egg • Skull • Brokers • Golem|