Even before Sanctuary was made, highways went from the high elven Silver Spires all the way to Thalassar. When Bahamut arrived he made sure that the Highway went to his sanctum (which was later destroyed in the Dragon Wars). Following the devastation from the Dragon Wars, the highways were slowly rebuilt. Today the highways are bustling with life, to the point where some make their living on the highway. Guides, peddlers and thieves fight for 'customers' every day, and it's arguably a moving city.
The Highway is the main trading and traveling route, stretching across all of western Malkor, going from Santuary to the North, diverging both towards the east and west. It's a simple, large dirt road, lit up at certain checkpoints and all crossroads by magical lights. At some checkpoints villages have sprung up, courtesy of having Peacekeeper fortresses built up many, many years ago, and individuals have stayed longer than one lifetime. Likewise, in more populated areas the Highway often changes to stone road and becomes more easy to travel.
Flora & Fauna
One of the populated checkpoints along the Highway have magically cultivated vegetables and fruits, and actively supplies its village as well as visitors with said food, but otherwise the Highway does not possess its own "unique" flora and fauna.
Though the road goes through many different biomes, the area around has been moved and terraformed to focus on comforting travel for horses and carriages; Trees and fields might grow on the side of the road, but they are not publicly available.