IGN Remonter le Temps Institut national de l'information géographique et forestière

History and Background

The Institut national de l'information géographique et forestière (IGN) is France's public national mapping authority, founded in 1940 to produce and maintain authoritative geographic information for France and its overseas territories. It is the successor to the Geographical Service of the Army, itself founded in 1887, whose origins trace to cartographic groups active since the early 18th century. In 2012, IGN merged with the National Forest Inventory (IFN) to assume its current name and expanded mandate covering both geographic and forest data.

Remonter le Temps

Remonter le temps (meaning "Travel Back in Time") is a dedicated IGN web service launched in 2016 that provides online access to historical maps and aerial photographs of France. The platform allows users to compare historical and current geographic data side by side, facilitating fine-grained analysis of how French territory has evolved over time. Historical aerial photographs, including those from the mid-20th century onward, have been digitized by IGN and are available for free download.

Collections and Holdings

The platform offers access to several landmark historical cartographic series, including the 18th-century Cassini maps, Napoleonic-era État-Major survey maps, and multiple generations of aerial photography from the 1950s to the present. Coverage includes metropolitan France, overseas departments and regions (with partial coverage of French Guiana), and overseas communities. The service provides three main functions: comparative viewing of historical and current imagery, access to aerial photo missions with associated metadata, and the ordering of printed historical map posters.

Access and Usage

Remonter le temps is freely accessible to the public at remonterletemps.ign.fr. Digitized aerial photographs can be visualized and downloaded at no charge. The platform is used by researchers, historians, planners, environmental scientists, and the general public for applications including land-use change analysis, urban history, coastal evolution monitoring, and heritage documentation.