Arcadia exists in the Dark Horse Universe although it has been referenced and visited by some DC Comics Characters like Oracle and Batgirl (Cassandra Cain). Arcadia is located on the eastern seaboard of the United States. It was once a great city that has fallen to corruption much in the same way the more famous Gotham City.
The city is recognized by the logo of balanced scales in a circle with a cross. This obviously stands for the city being unbalanced. The city is separated on two side of a body of water by a suspension bridge.
Events in Arcadia History
Arcadia is known to be the home city of the super-heroine known as the Ghost as well as X. Ghost has even worked with Oracle and Batgirl (Cassandra Cain) there while they fought one of her most dangerous foes the General (Malcolm Greymater) and the Trio.