This document describes a proposed mobile app called "The Time Machine" that would allow visitors to Balboa Park to explore the park and learn about its history by "dialing" into different time periods. Users could choose from time periods like the 1940s, 1915, or the 1870s to see snapshots of major events, cultural trends, photos, and context for both the world and Balboa Park at that time. They would then be able to view a list of related artifacts, places, figures, etc. and "collect" ones they discover on a virtual map of the park. The app aims to foster exploration, discovery, and collaboration between the park's institutions.