1. For use in conjunction with critical dimensions metrology of a semiconductor structure comprising a plurality of similar structural elements, said plurality of similar structural elements including at least a first group and a second group of similar structural elements, each group of similar structural elements originating from a different manufacturing stage, a computerized method of classifying the similar structural elements, the method comprising: obtaining a two-dimensional image of the semiconductor structure, said image comprising a plurality of similar two-dimensional image elements corresponding to said plurality of similar structural elements; identifying a sufficient number of structural elements belonging to the first group and a sufficient number of structural elements belonging to the second group; assessing to each identified structural element within said sufficient number of structural elements in the first group and in the second group one or more features associated with structural elements located adjacent to each of the identified structural elements that are indicative of a respective manufacturing stage; deriving, from the obtained two-dimensional image, values for the one or more features, thus giving rise to assessment results; and using said assessment results for a classification decision related to manufacturing stages and respectively originating therefrom structural elements in the first group and in the second group of similar structural elements.