Here is the full list of all 6 Monuments Flipper: Prologue achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Complete main task in Old Village.
Complete all main quests on the Aqueduct
Complete all tasks in the prologue.
Find all spear pieces, restore and reassemble.
Rebuild the Roman Crane.
Order the parts and build a wooden cantilever.