"overlooking a bleak and barren caldera"
Caldera on the Pico del Teide, Tenerife
Creative Commons AttributionCaldera on the Pico del Teide, Tenerife - Credit: Andys

A caldera (from the Latin caldaria, meaning ‘cooking pot’) is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption.

They are sometimes confused with volcanic craters. Technically, however, craters are found at the top of the central vent in  most volcanoes, while the caldera is a magma chamber that once supplied material to volcano until it emptied and the roof collapsed.