Castles in Spain are a popular tourist attraction due to their historical significance and stunning architecture. The term 'castles in Spain' is often used to refer to something that is impossible or unattainable. In this crossword, the solution for the term 'castles in Spain' is 'ROOKS, ' which is a type of chess piece. ROOKS are powerful pieces that can move in any direction and capture other pieces. They are often used to protect the king and queen pieces on the chessboard.