More than 3,000 maps of cities, battles and landscapes—representing a millennium of history—have been georeferenced by the British Library. That means it's now possible to see the precise locations of historic places and events in the context of today's world.
The BL Georeferencer allows you to click on points across the globe, revealing multiple views using street maps, satellite maps or even 3D topography, by means of Google Earth. The result is a stunning interface, allowing you to see how cities have changed over time, or gain insights into the landscapes where famous battles were fought. A sliding toggle allows you to alter the map's transparency.
An 1845 map of Salem, Massachusetts [street view]
1848 campaign sketches of the Mexican-American War [3D view]
A map of London as it appeared in 1828 [satellite view]
Test drive it yourself at the BL Georeferencer site.