Storage system

A storage system comprising:

• a first set of tracks extending in a first direction;
• a second set of tracks extending in a second direction transverse to the first direction, to form a grid comprising a plurality of grid cells,
• a framework structure on which the first set of tracks and the second set of tracks are received such that a stack of containers may be stored below the plurality of grid cells;
• a plurality of load-handling devices for lifting and moving containers stacked in stacks within the storage system, each of the load-handling devices being configured to move on the tracks above the stacks of containers at a top level of the grid;
• a rail received within the framework structure and underneath the top level of the grid;
• a robotic picking device comprising a robotic arm movably connected to the rail, such that the robotic picking device is received beneath the top level of the grid;
• and
• one or more picking zones adjacent to the rail wherein in use the load-handling devices are configured to lower containers to or to lift containers from the one or more picking zones.