DNA is not only a wonderful material for nanoscale construction, its hybridization or hydrolysis can be used to provide energy for synthetic molecular machinery. With DNA it is possible to design and build three-dimensional scaffolds, to attach molecular components to them with sub-nanometre precision – and then to make them move. I shall describe our work on assembly pathways, on autonomous, biomimetic molecular motors powered by chemical fuels and the use of synthetic molecular machinery to control covalent chemical synthesis. I shall also discuss the use of kinesin motor proteins to power synthetic devices.