Short answers, pulled from the story.
The Appian Way was begun by the Roman censor Appius Claudius Caecus in 312 BC as a military road to support Roman campaigns in southern Italy. The main section from Rome to Capua was started and completed in that same year.
The road was built to solve a supply problem that had defeated Rome during the First Samnite War: the Pontine Marshes blocked reliable troop movement and resupply to the south. The road ran straight across the marshes on a stone causeway, allowing Rome to move troops rapidly and keep them supplied during the Samnite Wars.
The section from Rome to Capua was 132 Roman miles, roughly 121 miles. From Capua to Brundisium (Brindisi), the road covered 233 Roman miles, or approximately 214 miles. Rome pushed the road all the way to Brundisium in 264 BC.
After Spartacus was defeated by Marcus Licinius Crassus at the Siler River in 71 BC, 6,000 surviving slaves from the revolt were crucified along the 200 kilometers of the Via Appia from Rome to Capua.
The Via Appia Antica is the ancient section of the Appian Way near Rome, distinguished from the Via Appia Nuova built in 1784. It is a free tourist attraction, restored for Rome's Millennium and Great Jubilee celebrations, and can be walked continuously for about 10 miles from near the Baths of Caracalla.
The Appian Way entered the UNESCO World Heritage List in July 2024.