Back to the list of advances
Fortification is an advance in Fall of Rome, a scenario in Civilization III: Conquests.
Civilopedia entry[]
As siege weapons are improved, so must the fortifications defending against them. Simply put, a change in one forces an evolvement in the other. The walls around a city must become thicker and taller. Battlements are surrounded by moats, sometimes filled with water, sharp projections, dangerous creatures -- or a combination of the three! Even the towers interspersed along a fortified wall must adapt as the weapons of siege warfare evolve; roofs are added, and firing ports are modified to better serve (or defend against) new weapons.