English: The Lilia at Rough Castle. These pits formed part of the forward (northern) defences of the Roman fort at Rough Castle, on the Antonine Wall. They were originally about 3 feet deep and probably held upright sharpened stakes; these pits were then concealed with brushwood. The defences here consisted of about ten rows of twenty pits each. These pits were opened up by excavation in 1903, and have been kept open since then.

The Romans called these defences "lilia". This literally means "lilies", a military euphemism referring to the plant of the same name. Julius Caesar used such a system of lilia in his siege of the Gallic city of Alesia in 52BC. (Compare the medieval "Trou de loup", and the "Punji Pit" of more recent warfare, both of which operated on the same principle.)

See also 84377.