This model shows the town and citadel of Belfort in the 18th century, after completion of the “grand project for the fortification of Belfort” that Vauban proposed in 1687.
Over six thousand workers toiled for sixteen years to carry out Vauban’s detailed plans, which included re-routing the Savoureuse River so as to double the size of the town. They built thick walls around the newly enlarged town, with towers at the corners for cannons and additional elements such as demi-lunes (half-moons) outside the walls to protect the gates and the corners.

Bust of Vauban by Antoine Coysevox, on display in the Belfort Citadel
Vauban at this time was the Commissaire general des fortifications de France, which meant that he travelled more or less constantly around the border regions of the kingdom, inspecting the fortifications and sending reports to Louvois, the Minister of War. After the death of Louvois in 1691, Vauban was allowed to write directly to the King, Louis XIV.
During his long career, Vauban conducted 53 sieges, using new tactics of his own devising. He also developed detailed plans for 33 fortresses or fortified cities and suggested improvements for some 300 others, according to a text in the Citadel of Belfort.
Other sources give variations of these figures, depending on what is counted as what. In Bordeaux, for example, he appears to have suggested only minor improvements after inspecting the Fort du Hâ in the city center, but in other places like Lille, Belfort and Besançon, his plans resulted in huge construction projects that took years or decades to complete. In Toulon, which he visited four times between 1679 and 1700, he not only strengthened the defenses of the harbor and the city, but also designed a huge arsenal in which up to forty ships could be built or repaired at the same time.

Part of Vauban’s city wall in Belfort (lower left)
In Belfort, some elements of Vauban’s fortifications still exist — parts of the city wall, for example, and some of the artillery towers — but not as many as in nearby Besançon. The difference is that major modifications were made in Belfort in the 19th century, in hopes that Belfort would be able to withstand a siege using the much more powerful artillery that had been developed in the meantime.
In the Franco-Prussian War of 1870-71, Belfort did in fact successfully withstand a 103-day siege, which ended only when the war was lost in the rest of France.

La corne Vauban, diagrams and text
This information panel on the rear slope behind the Belfort Citadel shows how Vauban designed his corne (= horn) elements to protect approaches to the Citadel.

Fortifications as seen from this text panel
Some of Vauban’s constructions were incorporated into the more massive nineteenth-century fortifications, but it’s hard to imagine (at least for me) how they must have looked in Vauban’s time.
Location and aerial view on monumentum.fr.
My photos in this post are from 2016. I wrote the text in 2020.
See more posts on Belfort, France.
See more posts on Sébastien Le Prestre, Marquis de Vauban.
It’s very impressive to consider the scale of the task involved here, especially moving a river to free up space for the town to grow!
Think 6000 men with picks and shovels.
Forts like this are so interesting to photograph, but hard to get the whole idea of them without a drone or something similar.
Yes, indeed. That’s why I’m so thankful that the French army used to commission artists to make these relief-map models at a scale of 1:600, as in my lead photo. Twenty-eight of these models are on display on the top floor of the Invalides in Paris: https://operasandcycling.com/musee-des-plans-reliefs/