The Archives of French Algeria

The Cassini Map

Picture 16

If you have found the towns and villages of your ancestors, and if you would like to see a map of them as they were before the Revolution,  we have a website for you. 

César François Cassini, third in a line of four astronomers, was born at the Observatory of Paris in 1714, where his father and grandfather had worked before he succeeded to the job.  In 1744, King Louis XV ordered that a topographical map of all of France be created, showing every city, commune, village and hamlet of the country, and including rivers, lakes and a perfect rendition of the coastline.  The Academy of Sciences, with Cassini at the head of the project, began the enormous task. Nearly fifty years later, Cassini was dead and the country was in chaos, but his son, who had succeeded him at the Observatory, completed the project and the map was published in 1793. It really is a magnificent achievement.

UPDATE 3 AUGUST 2021: While the website below still exists, the search function and map visualization no longer works well at all. The best place now to access the Cassini maps is the government website GéoPortail

You can see it on the interactive website . It is not entirely easy to use, and on our computer it works better with the browser Firefox than with Safari. It is in French, but not too difficult to figure out. Here, we will walk you through it.

The title page reads: Des villages de Cassini aux communes d'aujourd'hui ("from the villages of Cassini's time to the communes of today"). Firstly, be sure that you have pop-up windows enabled and not blocked.

Across the centre of the page you have:

ACCUEIL - Welcome

GLOSSAIRE - Glossary

AIDE - Help

MISE À JOUR - Updates


NAVIGATION - Navigation around the maps

INDEX - Index of all location names on the maps

CASSINI - a brief biography of Cassini and history of the maps.

SOURCES - an explanation and description of the 180 sheets that make up the whole map.

 Now, click on NAVIGATION. The map appears at Bourges. Below the map is a row of squares that are tools:

  • L = the legend of the map. Cities are indicated in capital letters and walls, if any, are shown. Burgs or towns, are indicated in bold Roman type; villages are in regular Roman type; hamlets and names of farms are in italics. A little castle is drawn for villages with a chateau.
  • The little red map of France gives a global view of the country. This is a little peculiar looking as the map is so detailed. You can click on this to get a closer view, and it takes a lot of clicks!
  • + = zoom in. You must click on the plus sign and then on the map. 
  • - = zoom out. Again, you must click on the minus sign and then on the map.
  • Hand = dragging 
  • + with a rectangle lets you draw a rectangular area in which you want to zoom in. 
  •  The empty magnifying glass lets you drag and zoom at the same time.
  • The N   gives you the modern name for the village. Click on the N, then on the map. This is a little clumsy, for not all villages have modern names and the map just keeps giving you the previous one. To make the name box go away, click any other of the tools.
  • The image of papers is a link to a wonderful page of information about the village. Click on the papers, then on the map, and a popup window will give information about the village you clicked on: the area of the village, the altitude, the longitude and latitude, the all important INSEE code, its administrative status and place in the administrative structure (which region, department and arrondissement it is in). Most preciously for genealogists, it gives all of the previous names it may have had and old departments and regions it was in. 
  • I = information on the sheet of that section of the map. Click on the i, then on the map, and a popup window tells of the size of the original, its number, the coordinates and scale of that section, the names of the departments it includes, the name of the engineer who did the surveying, and notes in the margins, and a link to see the original n the website of the Bibliothèque National de France, which does not always work.

At the top right is a small diagram of France and the departments, with a red circle that shows where you are generally. Also to the right are boxes to click on to show boundaries, but we find this cluttering. The two other key bits of information on the right are:

RECHERCHER UN LIEU...  which is the search function. Click on the words to get another popup window. If you know the department, select it from the drop down menu. We selected Dordogne. The four circles indicate how to search the name. Chaine exacte is "exact wording"; Commence is "begins with"; Contient is "contains"; Se termine is "ends with"; Avec article is if the name has an article such as Le, La, Les. The easiest is to leave the article box checked and choose contient. In the next box, type in the name of the town or village in which your ancestor lived. We typed Hautefort. Now, click RECHERCHER.

In the box below will appear all towns with that word, in this case, just one, though it could be many. Those in red are still in existence today. Those in green are previous names for existing villages. Those in black are places no longer in existence. Pay attention to the numbers in the parentheses. Those are the INSEE numbers for each location. The first two digits are those of the department. Click on the name you want to see, then click on CARTE to see it on the map or NOTICE COMMUNALE to get the same popup window with all of the information about the town as with N above. Click PLEIN ECRAN for full screen. Depending on how much you zoom, it will look like the map of Hautefort above.

To download, you must register. On the right, click TELECHARGER (which means "download") and a registration screen will come up. There is no charge to register. Just more loss of privacy. Alternatively, click IMPRIMER to print, which does not require registration.

Now, you can have some wonderful illustrative maps for your book on your French ancestors. Have fun.

©2009 Anne Morddel


French Genealogy

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