Abstract: A storage system includes a three dimensional structure including an array of cells including a plurality of cells configured to retain individual storage bins for retrieval, the array of cells forming a plurality of storage levels located at different elevations within the three dimensional structure, respectively. A second plurality of cells positioned relative to one another to form a plurality of vertical shafts located within the three dimensional structure. The storage system includes a plurality of towerbots located atop the three dimensional structure. Each of the towerbots is configured to move laterally atop the three dimensional structure between multiple different locations atop the three dimensional structure including at least a first position located above a first vertical shaft included in the plurality of vertical shafts and a second position located above a second vertical shaft included in the plurality of vertical shafts.