The Garda Lake is the largest and deepest lake in Italy and it was formed by a glacier during the last Ice Age. It is known for its beauty and for its unique climate: it is the only place in the Alpine region where Mediterranean plants like olive trees and citrus grow. In the peninsula of Sirmione on the south shores of the lake are a picturesque medieval town, a 13th century castle, and the ruins of an ancient Roman villa from the 1st century A.D.