With content generated by architects, historians, urban sociologists, and archaeologists, as well as the general public, HyperCities is a Google Maps mashup of historical maps of some famous world's cities. Currently the site has a series of historical maps for Berlin, New York, Los Angeles and Tel Aviv.
For each city the historical maps are listed under the Google Maps interface. Clicking on a year loads the historical map for that year as an overlay on top of Google Maps. The map markers on the map can also be viewed by their historical relevance. At the top of the map is a timeline slider which can be used to load map markers for any historical period.