Living systems achieve robust self-assembly across a wide range of length scales. In the synthetic realm, nanofabrication strategies such as DNA origami have enabled robust self-assembly of submicron-scale shapes from a multitude of single-stranded components. To achieve greater complexity, subsequent hierarchical joining of origami can be pursued. However, erroneous and missing linkages restrict the number of unique origami that can be practically combined into a single design. We have extended crisscross polymerization, a strategy previously demonstrated with single-stranded components, to DNA-origami “slats” for fabrication of custom multi-micron shapes with user-defined nanoscale surface patterning. Using a library of ~2000 strands that are combinatorially arranged to create unique DNA-origami slats, we have realized finite structures composed of >1000 uniquely addressable slats, with a mass exceeding five gigadaltons and with lateral dimensions of roughly two microns, as well as a multitude of periodic structures. Robust production of target crisscross structures is enabled through strict control over initiation, rapid growth and minimal premature termination, and highly orthogonal binding specificities. Thus crisscross growth provides a route for prototyping and scalable production of structures integrating thousands of unique components (i.e. origami slats) that each are sophisticated and molecularly precise.