Mount Etna is the highest European volcano, one of the most active in the world: it is a complex volcano but it is not considered particularly dangerous and thousands of people live on its slopes and in the surrounding areas. It looks like a truncated cone with a ragged top, which is actually a complex of large volcanic cones hosting four summit craters. The slopes of Etna form three distinct zones: the lowest is densely populated and planted with vineyards, citrus fruits, groves of olives and almonds. The middle zone is heavily wooded mostly with pine and chestnut trees while the top of the mountain is a volcanic wasteland, dominated by the old lava flows and volcanic ash. Few plants grow there because it is covered by snow for much of the year.