From the Guardian:

The plainest, strongest and oldest of the classical orders of architecture is the Doric, developed by mainland Greeks and familiar to us all in the form of the Parthenon.

Doric columns rest directly on the ground and support the beams above with a simple cushion, called an echinus, and a square plate, or abacus. The columns are 'fluted' with vertical grooves. The drawing on the left, from a handbook by modern classical architect Robert Adam, shows a column in Selinus in Sicily dating from the 6th century BC.

The first Doric columns were short and squat, only about four times as high as they were broad. This ratio gradually increased to a height of more than seven times the diameter, but Doric has always been regarded as the column to use to denote strength, masculinity and practicality.

When the Greek style was revived in Britain in the 19th century, Doric columns were used where these robust qualities were required. They were used sometimes on the ground floor to support the whole building, sometimes to symbolise military strength in forts and barracks, and often to show strength in industrial buildings.