This research tool includes planar (top-down) aerial photographs, satellite images, and a variety of maps. The historic date range runs from 1876, the year of the US centennial, to 2019, the year the refinery exploded for the last time. There are also future-oriented maps that visualize risk scenarios for flooding events and sea-level rise. All the cartographic scans have been georeferenced and georectified (pinned and aligned) so they can be layered for visual comparison. By layering and unlayering, and by zooming in and zooming out, you can see how the built environment has changed over time, and appreciate how those changes relate to social and physical factors. These layered maps have inherent visual interest, but you will gain more from them as you learn about Philadelphia and its fossil fuel history from the textual side of the website. Atop any layer, you can superimpose boundaries of the “Areas of Interest” (environmental remediation zones) that comprise the former refinery complex.