A storage system comprising: one or more storage/retrieval vehicles; a gridded three dimensional structure comprising: a plurality of storage cells arranged in stacks and each comprising a plurality of storage locations disposed around a central void on different respective sides thereof, each unit space being sized to accommodate a respective storage unit therein; each stack comprising a respective group of the storage cells residing in stacked relation one over another with the central voids of said respective group of the storage cells aligned with one another to form a respective upright central shaft of said stack; each central upright shaft being sized to accommodate the respective storage units of the respectively group of storage cells within said upright shaft to enable retrieval of said respective storage units through said upright central shaft; wherein the stacks of the gridded structure comprises full-sided stacks in which the upright central shaft is surrounded by the storage locations of the respective group of storage cells on four different sides of said upright central shaft; wherein the three dimensional grid structure further comprises shelving (112a, 112b. 112c) by which the storage units are individually supported bins to enable withdrawal of lower storage units from each stack without disruption to other storage units residing above said lower storage bins in the same stack; and further comprising a gridded track system (22, 24) on which said one or more storage/retrieval vehicles are each a) conveyable on said gridded track system to and from the upright central shafts; the storage system being characterized in that on the gridded track system (22,24) said one or more storage/retrieval vehicles are each b) conveyable through said upright central shaft to access the storage locations therefrom; and in that each of said one or more storage/retrieval vehicles comprises a rotatable turret and an extendable arm selectively extendable into a deployed position reaching outwardly beyond a perimeter of said turret, said turret being rotatable into four different working positions in which extension of the extendable arm will deploy said extendable arm outwardly from the turret at four different respective sides of the vehicle to access the storage locations on different sides of the upright central shaft of any one of the stacks. one or more storage/retrieval vehicles; a gridded three dimensional structure comprising: a plurality of storage cells arranged in stacks and each comprising a plurality of storage locations disposed around a central void on different respective sides thereof, each unit space being sized to accommodate a respective storage unit therein; each stack comprising a respective group of the storage cells residing in stacked relation one over another with the central voids of said respective group of the storage cells aligned with one another to form a respective upright central shaft of said stack; each central upright shaft being sized to accommodate the respective storage units of the respectively group of storage cells within said upright shaft to enable retrieval of said respective storage units through said upright central shaft; a plurality of storage cells arranged in stacks and each comprising a plurality of storage locations disposed around a central void on different respective sides thereof, each unit space being sized to accommodate a respective storage unit therein; each stack comprising a respective group of the storage cells residing in stacked relation one over another with the central voids of said respective group of the storage cells aligned with one another to form a respective upright central shaft of said stack; each central upright shaft being sized to accommodate the respective storage units of the respectively group of storage cells within said upright shaft to enable retrieval of said respective storage units through said upright central shaft; wherein the stacks of the gridded structure comprises full-sided stacks in which the upright central shaft is surrounded by the storage locations of the respective group of storage cells on four different sides of said upright central shaft; wherein the three dimensional grid structure further comprises shelving (112a, 112b. 112c) by which the storage units are individually supported bins to enable withdrawal of lower storage units from each stack without disruption to other storage units residing above said lower storage bins in the same stack; and further comprising a gridded track system (22, 24) on which said one or more storage/retrieval vehicles are each a) conveyable on said gridded track system to and from the upright central shafts; the storage system being characterized in that on the gridded track system (22,24) said one or more storage/retrieval vehicles are each b) conveyable through said upright central shaft to access the storage locations therefrom; and in that each of said one or more storage/retrieval vehicles comprises a rotatable turret and an extendable arm selectively extendable into a deployed position reaching outwardly beyond a perimeter of said turret, said turret being rotatable into four different working positions in which extension of the extendable arm will deploy said extendable arm outwardly from the turret at four different respective sides of the vehicle to access the storage locations on different sides of the upright central shaft of any one of the stacks.