Aincrad

Aincrad (アインクラッド, Ainkuraddo?) is the first «Realized World» shown in the Sword Art Online series and the stage for the first VRMMORPG, «Sword Art Online», created by Kayaba Akihiko.

Background
Aincrad is the world set as the stage for «Sword Art Online», declared to be the world's first VRMMORPG in history. It was incorporated in «ALfheim Online» on May 2025.

The base currency of Aincrad is the Col.

Etymology and Meaning
The castle's name came from the concept of a «Realized World», called An Incarnating Radius (アン・インカーネイティング・ラディウス, An Inkāneitingu Radiusu?), which has been abbreviated as Aincrad.[1] It is also inferable that its design is symbolic for time and space. The vertical axis represents time and the circular floors represent space.[2]

Geography
Aincrad is an iron-and-stone made floating castle that has about ten kilometers floor base diameter and consists of a hundred floors stacking straight upwards, meaning that each floor's diameter is a bit smaller than the previous one. On each floor, there are a couple of large cities along with countless small scale towns and villages, forests, plains, and even lakes. Only one stairway links each floor to another, and the stairways exists beyond the boss room of each dungeon. The «Teleport Gates» of every unlocked city are connected to one another.