Many innate behaviors are the result of multiple sensorimotor programs that are dynamically coordinated to produce higher-order behaviors such as courtship or architecture. Extended phenotypes such as architecture are especially useful for ethological study because the structure itself is a physical record of behavioral intent. A particularly elegant and easily quantifiable structure is the spider orb-web. The geometric symmetry and regularity of these webs have long generated interest in their behavioral origin. However, quantitative analyses of this behavior have been sparse due to the difficulty of recording web-making in real-time. To address this, we have developed a novel assay enabling real-time, high-resolution tracking of limb movements and web structure produced by the hackled orb-weaver Uloborus diversus. With a brain the size of a fly’s, the spider U. diversus offers a tractable organism for the study of complex behaviors. Using machine vision algorithms for limb tracking, and unsupervised behavioral clustering methods, we have developed an atlas of stereotyped movement motifs used in orb-web construction. The rules for how these motifs are coordinated change during different phases of web construction, and we find that we can predict web-building stages based on these rules alone. Thus, the physical structures of the web explicitly represent distinct phases of behavior. In addition to our behavioral efforts, we are also developing biological assays to investigate how this elegant behavior is encoded in the spider’s brain.