Petrified forest of Lesvos

Wait, this isn’t as scary as it sounds! After a volcanic eruption almost 20 million years ago, the trees in this forest were basically frozen in time after being covered in lava and ash. The wood changed to stone as a result and you can see some of them still standing in their fossilised form today. This UNESCO World Heritage Site also has a natural history museum open daily where you can delve into the details. Plus it's in the beautiful harbour town of Sigri.