2. Calendar Man's Cell
Calendars play a major part in Batman Arkham Origins, from the early trailer that featured one calendar with days marked off leading up to Christmas Day (though the events of the game actually happen on Christmas Eve) and following on from a trend established in earlier Arkham games, Origins features a reference to Calendar Man. It is possible to visit Calendar Man's cell, which is covered in calendar pages, and features scrawled wall messages relating to key calendar events such as New Year's Day. Calendar Man's presence might not be as major as some of the other villains, but this is certainly a good nod for fans of the character, who became an iconic figure in the wake of The Long Halloween, and though there's no option for a Year One style Achievement, as there was in Arkham Asylum, this sort of detail is what Batman fans eat up.