Art gallery:
Collect all artifacts in the game to unlock an art gallery. 

Hints: 
Avoid falling damage:
Press R1 as before you hit the ground to enter combat mode. You will not get any 
damage from falling. 

Pistol whip:
Press Square to pistol whip your adversary. Note: This works for all guns, not just 
the pistols. 

Drink from canteen:
To drink from the canteen, hold X. If you instead tap X, it will take longer. 
Holding X also helps when you fill your canteen. 

Magical barrier:
Equip the PaCheng and press R1 to block. 

Break wall in Istanbul Sunken City: 
When you reach Istanbul Sunken City, to break the damaged wall, hover above 
the head in the water with the crane. Press X and it will automatically break it up. 

Items from boxes:
Press Square to break boxes then press Triangle to pick up the item. Note: Note 
all boxes contain items.