Radiata Castle is a castle at the center of Radiata where the Radiata Knights reside. The king and his family lives in the upper floors, where the regular members of the castle cannot go. A number of nobles and their families also live in the castle, including the Prime Minister.
The castle is made up of five floors and two basements, one of which is in two halves. There is a wind-powered elevator that connects floors 1~4. There's a long staircase on one end of the building that connects the two basements, floors two and three as well as the parts of the Path of the Spider that are connected only to the castle.