Nine major historical city-states and urban centres of ancient Mesopotamia along the Tigris and Euphrates rivers.

The four anatomical lobes, key dividing sulci, and the olfactory bulb of the human brain in lateral view.

The nine principal veins responsible for returning deoxygenated blood to the heart.

The key reproductive stages of a gymnosperm pine tree from cone formation to a young seedling.

The nine primary external parts and flight control surfaces of a commercial airplane.

The eight planets of the Solar System in orbital order along with the main asteroid belt.

The essential structural layers and components of a photovoltaic solar panel.

United Kingdom: boundaries + main cities + names

The 14 most typical playing positions in a football lineup.