1. A system for displaying groups of cluster spines, comprising: obtaining groups of cluster spines, each group comprising one or more spines with one or more document clusters each associated with at least one concept; a vector module to generate group concept score vectors for each of the spine groups by aggregating the concepts for the clusters in that spine group; a comparison module to compare the group concept score vectors for each of the spine groups and to identify those spine groups that are unique; and a placement module to place the unique spine groups into a display by arranging the unique spine groups at equal distance angles around a ring provided centrally in the display.