There are two types of roads: dirt roads and cobblestone roads. Carts and inhabitants travel faster over cobblestone roads, allowing faster collection of resources and faster movement of surgeons and firefighters, for example. When possible, always pave the roads connecting your resource-production facilities with cobblestone.
When built over rivers, dirt roads produce wooden bridges (see image below), as opposed to cobblestone roads which produce stone bridges.
- ↑ Prima Official Dawn of Discovery Guide