The below cheats work on all consoles.

Code	Effect
Et In Arcadia Ego	All bonuses Unlocked
Apocrypha	All Visual Database entries Unlocked
Sacred Feminine	Double Health
Vitruvian Man	God Mode (infinite health)
Clos Luce 1519	Level Select
Phillips Exeter	One Hit Fist Kill
Royal Holloway	One Hit Weapon Kill

The following is for the PC game only

Secret Levels

Earn these levels by completing the game.

Unlockable	How to Unlock
Rosslyn Chapel Revisited	Complete the game.
The Louvre Revisited	Complete the game.