Within cells, nanostructures are often organized using local assembly rules that produce long-range order(1,2). Because these rules can take into account the cell's current structure and state, they can enable complexes, organelles or cytoskeletal structures to assemble around existing cellular components to form architectures(3-6). Although many methods for self-assembling biomolecular nanostructures have been developed(7-11), few can be programmed to assemble structures whose form depends on the identity and organization of structures already present in the environment. Here, we demonstrate that DNA nanotubes can grow to connect pairs of molecular landmarks with different separation distances and relative orientations. DNA tile nanotubes nucleate at these landmarks and grow while their free ends diffuse. The nanotubes can then join end to end to form stable connections, with unconnected nanotubes selectively melted away. Connections form between landmark pairs separated by 1-10 mu m in more than 75% of cases and can span a surface or three dimensions. This point-to-point assembly process illustrates how self-assembly kinetics can be designed to produce structures with a desired physical property rather than a specific shape.