Bordeaux town hall has been set on fire as French protests continued over plans to raise the pension age.
More than a million people took to the streets across France on Thursday, with 119,000 in Paris, according to figures from the interior ministry.
Police fired tear gas at protesters in the capital and 80 people were arrested across the country.
The demonstrations were sparked by legislation raising the retirement age by two years to 64.
Unions have called for further protests next Tuesday, which would coincide with King Charles III's state visit to the country.
He is scheduled to be in the southwest city of Bordeaux on that day, where fire engulfed the front door of the town hall on Thursday evening after a day of protests and clashes.
It was not clear who was responsible for the blaze, which was quickly put out by firefighters.
Interior Minister Gérald Darmanin sought to quell any concerns ahead of the King's trip, saying on Thursday night that security "poses no problem" and the monarch will be "welcomed and welcomed well", according to AP.
In Paris, generally peaceful demonstrations saw occasional clashes between police and masked rioters who smashed shop windows, demolished street furniture and attacked a McDonald's restaurant, according to Reuters news agency.
One police officer who lost consciousness was dragged to safety.
AP news agency reported that police forces used tear gas and were pelted by objects and fireworks, with 33 people arrested in the capital.
France's Prime Minister, Élisabeth Borne, tweeted: "Demonstrating and voicing disagreements is a right. The violence and degradation we have witnessed today is unacceptable. All my gratitude to the police and rescue forces mobilized."
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