A method of fabricating a two dimensional nano-structure array of features comprising the steps of providing a substrate (10); forming an intermediate layer on said substrate (20), said intermediate layer having at least two selectively located regions (21, 22) of different uniform thickness; placing at least one layer of elements (30) over said intermediate layer, said elements placed in a close-packed arrangement forming an array of voids (33) between said elements; etching the intermediate layer through said voids, and so forming the array of features (51, 52) in said intermediate layer corresponding to the voids.