A team of Danish economists have argued that European roads built by the Romans 2,000 years ago played a decisive role in the modern economic development of the Continent, the Washington Post reports.

According to the economists’ research, the density of roads and trade links originally laid down during the periods of when the Roman Republic (second century BCE – first century AD) expanded beyond the Italian peninsula and during the Empire (first century AD – fifth century AD) correlates to the modern level of prosperity for most European cities and countries. The research team went on to say that the study shows the importance of investing in vital infrastructure as it serves as the main driver of economic development.

The Danish team based their observations on a geographic database for Roman road networks that were compiled by Harvard University’s Digital Atlas of Roman and Medieval Civilizations. The database documents the 80,000 kilometres of roads that the Romans developed across Europe, the Near East, and North Africa during the seven centuries when Rome was the preeminent power in the Western World.

Part of the research included superimposing the maps of Roman roads over satellite imagery showing the nighttime illumination of Europe in 2010. The Danish team then divided the entire former Roman Empire into a grid of one-degree latitude by one-degree longitude squares and measured the density of Roman roads. They then compared this with the density of modern-day population centres and, once again, found strong evidence that the roads not only facilitated trade, but also innovation in transport and productivity. The infrastructure that developed around those industries most likely had a cumulative effect over the centuries and later became the foundation for urban development across Europe.

The researchers believe that after Rome’s road system fell into disrepair in North Africa following the empire’s collapse in 476 AD is one explanation for the economic development gap between Europe and other parts of the Middle East that remained a part of the Greek-speaking Byzantine Empire that emerged following Rome’s demise.