Croatia

In central Dalmatia, in Krka National Park, there are the ruins of a hydroelectric power plant built in 1895.

An excerpt from the article 51 facts about Croatia
The Krka hydroelectric power plant is the second of its kind in the world, the only one older than it was the hydroelectric power plant on the Niagara River, which was built on Nikola Tesla's initiative. Today, Croatia's first hydroelectric power plant is no longer in operation. Still, because of its importance in the history of technology, restoration work is being carried out.

Not far from the first hydroelectric power plant, the hydroelectric power plant "Jaruga," constructed soon after the first one, is still in operation today. It is quite a rarity in modern times.