Turin's firefighters are handling a blaze at Cavallerizza Reale, a famed UNESCO World Heritage, Italy's fire department said.
A portion of the roof collapsed after catching fire, firefighters said on Twitter.
While the blaze is now extinguished, final operations are still "in progress," according to the fire department.
Cavallerizza Reale was built around 300 years ago as a military academy for senior officers from the royal House of Savoy.