Here is a guide on how to find all hidden statues. SPOILERS!
NEPTUNUS
On the left side between first and second aqueduct:
At the end of main road, to the left of third aqueduct:
On the right side of entrance to the third aqueduct:
At the end of main road, to the left of third aqueduct:
On the right side of entrance to the third aqueduct:
TELLUS
While solving bridge puzzle at the farthest end of this map:
SOMNUS
On the left side when you arrive to the big lake:
MINERVA
Far on the left side when you start this level:
Thanks to DDtective for his great guide, all credit to his effort. you can also read the original guide fromĀ Steam Community. enjoy the game.