My campaign has just finished Hoard of the Dragon Queen, and the players want some downtime activities. I'd like to give them the option of renovating the Hunting Lodge they captured from Talis, and also help renew the quality of life in Parnast after long occupation by cultists.
So I'd like to give them a bunch of possible investments for their newfound fortune. Are there standard costs for roads of various types (dirt, clay, paving stones) in various environments (mountains, forest, swamp, etc)? What about town walls, defenses (wood, stone, guard towers)?