This impressive ditch at Crookston Castle is all that remains of the first castle built here around 1145. The name 'Crookston' comes from a family of huntsmen. Sir Robert Croc laird of Cowglen in the 12th century carried three forester's crooks on his shield. In the 14th century they lost their land and most of the Levern Valley was aquired by a branch of the Stewarts. Map location.