At its height the Roman Empire was joined by more than 80,000 kilometres of paved roads. Many were built by soldiers, so that armies could march quickly to any frontier.
A typical road was built in layers: a deep trench filled with large stones, then gravel and sand, then tightly fitted paving slabs on top. The surface was curved so that rain ran off into ditches on either side.
Some of these roads, such as the Via Appia south of Rome, can still be walked on today, and many modern European highways follow routes first laid out by Roman surveyors.
