Here is the full list of all 19 Marble Age achievements.
Beat the game for Athens.
Complete the trial Arab Invasion.
Complete the trial Justinian Plague.
Complete the trial Huns Invasion.
Complete the trial Christianity.
Complete the trial Greek Campaign.
Unite Greece.
Complete the trial Scythian Invasion.
Complete the trial Roman Menace.
Complete the trial Persian Invasion.
Complete the trial Dorian Invasion.
Unite the world.
Beat the game for Sparta.
Get more than 40 final score points.
Get more than 90 final score points.
Get more than 150 final score points.
Get 190 final score points playing for Sparta on Hard difficulty.
Get 200 final score points playing for Athens on Hard difficulty.
Get maximum final score points without using Civilization Points on Hard difficulty.