DNA-based nanotechnology is currently being developed for use in biomolecular computation, fabrication of 2D tile lattices, and engineering of 3D periodic matter. Here we present recent results on the construction and characterization of DNA nanotubes – a new self-assembling superstructure composed of DNA tiles. Triple-crossover (TAO) tiles modified with thiol-containing dsDNA stems projected out of the tile plane were utilized as the basic building block. TAO nanotubes display a constant diameter of approximately 25 nm and have been observed with lengths up to 20 microns. We present high resolution images of the constructs from transmission electron microscopy (TEM) and atomic force microscopy (AFM) as well as preliminary data on successful metallization of the nanotubes. DNA nanotubes represent a potentialb reakthrough in the self-assembly of nanometer scale circuits for electronics layout since they can be targeted to connect at specific locations on largerscale structures and can subsequently be metallized to form nanometer scale wires. The dimensions of these nanotubes are also perfectly suited for applications involving interconnection of molecular scale devices with macroscale components fabricated by conventional photolithographic methods.