The Petrified Forest Park of Sigri is a striking open-air natural museum on the western side of Lesvos island, near the small village of Sigri.

It feels almost otherworldly. Scattered across a dry, volcanic landscape are fossilized tree trunks—some standing upright, others lying where they fell—preserved in stone for about 20 million years. These trees were once part of a lush subtropical forest, but volcanic eruptions buried them in ash, cutting off oxygen and slowly replacing their organic material with minerals. That’s how they turned into stone while keeping their original shape.