The Persians, who lived in present-day Iran, were one of the first civilizations to build tunnels that provided a reliable supply of water to human settlements in dry areas. In the early first millennium BCE, they introduced the qanat method of
tunnel
construction, which consisted of placing posts over a hill in a straight line, to ensure that the Use synonyms
tunnel
kept to its route, and Use synonyms
then
digging vertical shafts down into the ground at regular intervals. Underground, workers removed the earth from between the ends of the shafts, creating a Linking Words
tunnel
. The excavated soil was taken up to the surface using the shafts, which Use synonyms
also
provided ventilation during the work. Once the Linking Words
tunnel
was completed, it allowed water to flow from the top of a hillside down towards a canal, which supplied water for human use. Remarkably, some qanats built by the Persians 2,700 years ago are still in use today.Use synonyms
omidateur