The authors are evaluating 3D game engine software to integrate GIS topographic survey data with photogrammetry as they build a virtual tour of a heritage site. The virtual tour will describe building exteriors and interiors, plus historical artifacts within the buildings that visitors should be able to examine from all angles on screen. The interface must be lightweight to run smoothly on mobile devices and must efficiently filter out information to guide the visitor to focal points. We seek to avoid the "black box" problem of locking the data in interface software, and rather, our data must be (con)served in openly accessible and readily queryable formats like CityGML, CityJSON, or simple CSV files. The authors will discuss their decisions for sustaining and sharing the project data, and their evaluation of 3D game engine software for its capacities to translate spatial data and to support annotation and user interactivity.