Abstract: A grid framework structure for supporting a load handling device operative to move one or more containers in a stack. The grid framework structure includes plural upright columns arranged to form plurality of vertical storage locations for containers to be stacked between upright columns. The columns are interconnected at their top ends by a first set of grid members and a second set of grid members, the second set running transversely to the first set to form a grid structure. A sub-group of upright columns rigidly joined together by at least one bracing assembly of diagonal braces form a braced tower. The sub-group of upright columns includes three upright columns with two of the three upright columns being laterally disposed either side of a middle upright column, and being rigidly connected to the middle upright column by the diagonal braces.