Short answers, pulled from the story.
The Roman censor Appius Claudius Caecus ordered the construction of the Appian Way in 312 BC. He began building a stone causeway across the Pontine Marshes without waiting for Senate approval.
Rome needed the road to move troops and supplies quickly through the malaria-infested Pontine Marshes between Rome and Capua. Previous attempts to cross this terrain had failed or been too slow to support armies fighting against mountain tribes like the Samnites.
Builders laid small stones and mortar as a base before covering it with gravel and tightly fitting interlocking volcanic rock layers. Some sections featured lime cement which may have been first used on any Roman road while retaining walls protected drainage channels along sunken portions.
Six thousand slaves were crucified along the route from Rome to Capua after Spartacus's revolt ended in 71 BC. Marcus Licinius Crassus defeated the slave army while Romans judged these slaves had forfeited their right to live as a warning to others.
The Appian Way entered UNESCO World Heritage List status in July 2024 after centuries of decline. The longest stretch of straight road in Europe totals approximately 132 Roman miles along its path through the region.