A simple and scalable approach for the hierarchical assembly of 2D and 3D ZnSe nanowires by the Langmuir-Blodgett technique was presented. The nanowires are assembled in a controlled way into a parallel array without deviation over a large area. The layer-by-layer assembly of crossed and related structures with a precisely controlled pitch and without the use of any secondary patterning technique was demonstrated. TEM image of individual wires shows well-resolved lattice plans with an inter-planar distance of 0.33±0.02 nm, consistent with wurtzite ZnSe. Semiconductor nanowire sensor arrays and nanoelectronic circuits with ultrahigh junction densities can be realized if electrical contact is achieved to make these nanowires addressable.