Collect all Bronze rewards from the following levels to unlock the concept art

Unlockable - How to Unlock

Bolivia - Collect all bronze rewards from Bolivia
England - Collect all bronze rewards from England
Ghana - Collect all bronze rewards from Ghana
Japan - Collect all bronze rewards from Japan
Kazakhstan - Collect all bronze rewards from Kazahkstan
Nepal - Collect all bronze rewards from Nepal
Peru - Collect all bronze rewards from Peru
Special - Collect all bronze rewards from Croft Manor