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.
Classic consists of 8 sets that ran from 1978 to 1984. As of today,
375-2 Castle is the most valuable Classic set with an estimated new/factory sealed value of $10,921.
Summary
Castle Classic Knight's Procession set 6077 was released in March 1990, retailing for $5, but has since been retired. New, unopened Knight's Procession sets are valued at $505, while used sets can be found for $80 in good condition.
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