NEW · TEN EVENT THEMES
Explore 2,657 events across the United States
Murders and assassinations, mysteries, disasters, battles, protests, science and culture. Filter by theme and year; follow the sources behind each record.
Thousands of places · 1920–today
Every place remembers.
Peel back the layers.
PlaceLayers maps what happened at exact spots on Earth — moment by moment, photograph by photograph — and lets you slide between the map of then and the map of now.
Stylised illustration — one viewpoint, five centuries. The documents behind moments like these live on the map.
2,510moments 114countries 1920–2025covered 2,238photographs
2,510 moments, on one map
Every pin is a documented event, 1920–1995, tied to the place where it happened. Click any pin.
Base map: USGS The National Map. Hold Ctrl (⌘ on Mac) and scroll to zoom, or use the buttons.
Then and now, one slider
Drag the handle. Baltimore as the USGS surveyed it in 1908, against the 1984 sheet. Open the full overlay tool to fade any historical map into today’s.
1908
1984
Left: Patapsco quadrangle, 1908, 1:125,000. Right: Baltimore quadrangle, 1984, 1:100,000. Both U.S. Geological Survey, public domain. The two sheets differ in scale and extent, so treat the alignment as illustrative — the overlay tool georeferences them properly.
Researching a Baltimore property?
The property-history wing of PlaceLayers: Sanborn fire-insurance sheets that letter the use of every building, historical USGS quadrangles, and plain-language guides. Scope today: Baltimore, Maryland, 18 indexed streets and 283 digitised sheets — growing city by city.
Baltimore coverage & sheet browser Former-use decoder Build a research plan
Everything on PlaceLayers is a primary document or points to one: every photograph carries its licence and author, every event its source. We record what happened at places — we do not assess, rate or score any property. How we work, and the limits.