Maps are an integral part of modern life, but they typically lack historical context. A new tool called Pastmaps offers a fascinating way to explore the past of cities. This website allows users to see what locations looked like decades or even centuries ago. Users can easily access Pastmaps in any web browser and select a U.S. city to begin their exploration. After searching for a city, Pastmaps presents a list of historical maps from various time periods. Selecting a map reveals an interactive historical view of the area. A unique feature is the opacity slider, which allows seamless fading between the historical map and the current view. This tool provides a compelling way to observe urban evolution over time. Pastmaps is web-based, requiring no downloads and offering free access to a limited number of maps weekly. For unlimited use, a small annual subscription is available, but free access is ample for casual users.