RuneScape Classic Wiki
RuneScape Classic Wiki
The main RuneScape Wiki has an article on: White Knights Castle
The Old School RuneScape Wiki also has an article on White Knights Castle.
RuneScape uses the British convention for floor numbering: ground floor, first floor (immediately above the ground floor), second floor, etc.

Screenshot of the White Knight's Castle.

The White Knights Castle is located in central Falador, surrounded by a moat. It is inhabited by several attackable white knights (Level - 56) and a chicken (Level - 3). There are also three quest characters in this area: