You'll need to collect all of these artifacts if you plan to unlock all of the trophies in the game.
Here are the ten hidden artifacts you can collect sorted by chapter, and how to find them.
Chapter 2 – The Sewers
Prisoner's Oath Stone – After exiting the sewers, look for a wall that you can climb. Pull the lever on the other side, which pulls up a gate letting three Goat Warriors free that will attack you. You'll find the artifact behind the gate that the enemies came from.
Chapter 5 – The Village of Kirra
Circe's Vial – Once you beat the two Juggernauts, proceed right and then left. Jump onto the moving cage, then onto the balcony, and you'll find the artifact inside.
Chapter 9 – Ice Caverns
Oracle Seeker's Offering – When you return the three snakes, you'll see a short cutscene showing how the towers get activated. Go inside the first tower, but instead of going up go to the very bottom of the tower to find the artifact.
Chapter 11 – Delphi Catacombs
Aletheia's Charm – When you pass the pendulum and hour glass section, you'll come to a throne. You'll find the artifact on the ground to the right of the throne.
Chapter 15 – The Grotto
Boat Captain's Idol – After you beat the two Ice Warriors, you'll have to destroy two metal chains to open a next door. Dive into the water in the next area, and follow the underwater path. When the path splits, go down and you will find the artifact lying at the bottom.o
Chapter 16 – Prison of the Damned
Orko's Cloak – After the cutscene with the flying woman in a cloak, look behind you for a blue and a green orb chest. To the right of the chest, look for a hidden area in the corner to find the artifact.
Chapter 21 – The Forearm of Apollo
Stonemason's Chisel – After you use the Oath Stone of Orkos to get up the elevator, go right and look for a hidden alcove to find the artifact.
Chapter 23 – The Furnace
Archimedes' Treatise – After the area that you have to cross using the platforms, you'll find the artifact on a table next to the body of Archimedes.
Chapter 25 – The Furnace Part 2
Statue Worker's Idol – After you pull the lever to reveal the bright light, you'll find the artifact in the top left corner of the platform.
Chapter 28 - Trial Of Archimedes
Antikythera Mechanism – After you finish the Trial of Archimedes, go back through the portal and a platform will bring you down to a lower level. When the platform stops, you'll find the final artifact up the stairs and to the right.