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Mont-César - English version

For lovers of history

Despite its prestigious name, Mont-César has nothing to do with the fortified camp of the Bellovaci tribe from which, in 51 BC, the Gallic chieftain Correus launched a final assault against the Roman troops and lost his life.

However, this site was occupied as early as the Bronze Age (1800 to 750 BC) and the Gauls later built an oppidum or fortified settlement on the hill. Oppida were veritable villages, whose name was coined by Julius Caesar in his "Commentaries on the Gallic War". The Gauls cleverly took advantage of natural landscape features, choosing elevated, steep-sided sites for their settlements.


It was the archaeological discoveries made during the 19th century that lent this hill its current name: coins, pottery, utensils, weapons and diverse other objects were dug up, testifying to the site's occupation by the Gauls and later the Romans.

Following the excavations, the site's history was marked by the grazing of sheep, which continued up until the 1930s.


The historic significance of Mont-César led to its being listed as a historic monument in 1979.

Today, the hill is a popular destination for walkers and its biodiversity is preserved by the joint efforts of the municipality of Bailleul-sur-Thérain and the Conservatory of Natural Sites in Picardy.

Did you know ?

So where are the vestiges of the Gallic fortifications? Over the centuries, the stones were used by the area's inhabitants for the building of houses, as has so often been the case.


The hill, rising to an altitude of 138 metres, is mostly wooded, except for the southern slope, consisting of a calcareous soil called larris in Picard. Unsuited to the growing of crops, this chalky soil produces herbaceous vegetation ideal for the grazing of sheep.


Today, only 5% of Picardy's land is made up of larris, making Mont-César all the more valuable a site.

Hidden treasures

Mont-César is home to a great diversity of flora and fauna. Bird watchers can admire the European stonechat, the Bruant zizi and the Eurasian hobby. The hill's reptile family includes the very rare and discreet Coronella austriaca, a perfectly harmless snake, and the viviparous lizard, which enjoys sunning itself on the grassy southern slope.


Amateur botanists will be delighted to discover several species of wild orchid, such as the fragrant orchid, the lady orchid, the lizard orchid and the Platanthère des montagnes. May and June are the best months for admiring these species.