The volcanic caldera of Agra, with a diameter of 6.5 kilometers, is one of the newest volcanic structures on Lesbos and is located south of the older caldera of Vatoussa.
The volcano of Agra is connected to the latest volcanic activity of Lesvos which started 17 million years ago. Successive volcanic eruptions formed the well-preserved caldera.The settlement of Agra is built on the western inner side of the caldera. The hills that surround Agra today form the limits of the caldera.Despite the long time that has passed since the volcano was active, it preserves the characteristic shape of the caldera better than any other structure.More recent tectonic activity created the outlet of the hydrographic network on the south side of the caldera that drains the volcanic basin.