A fire burned through one of the most well preserved medieval castles in Slovakia Saturday, destroying a significant portion of the 14th-century national monument.

The fire at the Krasna Horka castle started after the last tour of the day had ended, the BBC said.

There were no visitors inside when flames from a nearby grassfire spread to the castle’s wooden roof. The grassfire was set intentionally, firefighters told the Slovak Spectator, the only English-language newspaper in Slovakia.

Krasna Horka is near the Slovak town of Roznava. It is considered one of the most well-preserved castles in the region and is a National Cultural Monument of the Slovak Republic. The BBC said many of the artifacts inside the castle may have been destroyed.

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