DNA has many physical and chemical properties that make it a powerful material for molecular constructions at the nanometer length scale. In particular, its ability to form duplexes and other secondary structures through predictable nucleotide‐sequence‐directed hybridization allows for the design of programmable structural motifs which can self‐assemble to form large supramolecular arrays, scaffolds, and even mechanical and logical nanodevices. Despite the large variety of structural motifs used as building blocks in the programmed assembly of supramolecular DNA nanoarchitectures, the various modules share underlying principles in terms of the design of their hierarchical configuration and the implemented nucleotide sequences. This Review is intended to provide an overview of this fascinating and rapidly growing field of research from the structural design point of view. In the past 20 years, DNA has been established as a powerful material for molecular constructions at the nanometer scale. The ability to design building blocks from DNA containing well‐defined secondary structure motifs (a–f, in the scheme) allows the assembly of large supramolecular arrays, scaffolds, and even mechanical and logical nanodevices.