The Castle theme is one of LEGO’s primary themes first introduced in 1978 and based around medieval life with castles and knights. It is currently the third longest-lived theme in LEGO history. Over the years it saw numerous changes thus introducing various fantasy elements.
2006 LEGO Sets
2006 for LEGO was a year of new themes being introduced and a number of well known themes being retired. LEGO in 2006 introduced and discontinued The Avatar: The Last Airbender, introduced the original Batman theme, Exo-Force, Mindstorms NXT, SpongeBob SquarePants, Remote control Trains and Aqua Raiders. However, the following themes were discontinued; Clikits, Vikings. While LEGO Sports was re-introduced in 2006 with a couple Soccer/Football sets.