An alignment mechanism for a robotic parking device is described. The device includes a number of stacks of containers, the stacks being positioned within a frame structure having uprights and a horizontal grid disposed above the stacks, the grid having substantially perpendicular rails on which load handling devices can run. Cars or vehicles are positioned in containers that are moved in to and out of the stacks by the robotic handling devices. The cars are put in to the grid at entry points that can be positioned at points under the stacks. The alignment mechanism includes a series of belts moveable relative to each other and relative to the container, the belts acting to align a long axis of a vehicle with a long axis of the container in to which the vehicle is to be placed.