The fortifications in this model were designed by Vauban in the seventeenth century, but the topography was the same when Julius Caesar came through with his army in the year 58 BC. His description of Besançon (then known as Vesontio) is in Book 1 (Chapter 38) of his Commentarii de Bello Gallico (Commentaries on the Gallic War).
There, Caesar wrote that “the river Doubs almost surrounds the whole town, as though it were traced round it with a pair of compasses. A mountain of great height shuts in the remaining space, which is not more than 600 feet, where the river leaves a gap, in such a manner that the roots of that mountain extend to the river’s bank on either side. A wall thrown around it makes a citadel of this mountain, and connects it with the town. Hither Caesar hastens by forced marches by night and day, and, after having seized the town, stations a garrison there.” (Quoted from: www.gutenberg.org.)
The model in these photos is in the Musée du temps (Museum of time) in Besançon. It is a replica of an eighteenth-century model that has been preserved (but is currently not on display) at the Invalides in Paris.
In Besançon it is easy to get the impression that local history began in the 16th century with Charles V, or in the 17th century with Vauban, but actually the city is much older than that. Some remnants of ancient Vesontio, including eight Corinthian columns, can be seen at Square Castan. The square was named after the archeologist, librarian and local historian Auguste Castan (1833-1892), who systematically excavated the site starting in 1870.
Location, aerial view and photos of Square Castan on monumentum.fr.
My photos in this post are from 2014. I revised the text in 2019.
See also: my Geneva post on Clémentine (scroll down for Julius Caesar).