Historical inquiry involves investigating compelling questions by analyzing historical sources to construct evidence-based accounts of the past. However, teaching students to do history is challenging. This paper discusses the design of CI-Spy, a mobile augmented reality system that explicitly teaches inquiry strategies and engages students to practice the doing of history in an augmented real-world context. As a case study for the design of the application, we designed and embedded multiple augmented reality activities within an instructional unit using a local historic site (the Christiansburg Institute, or CI). We conducted a pilot study with elementary students to learn how and to what extent AR technologies can support learning inquiry strategies and processes. After using our system, students demonstrated a greater understanding of inquiry and gained significant insight into the hidden history of CI.