Riddler Map

The Riddler spread many different Riddles, Trophies, etc for Batman to find. Aside from those, he hid maps, which told Batman the locations of the Riddler Trophies in the surrounding area.

Arkham Asylum Incident
There's a Riddler Map in each location:
 * Secure Transit: in front of the entrance to Killer Croc's Lair, on the desk in a small nearby office.
 * Arkham East: the small office in front of Quincy Sharp's Statue (to get in the building, you need the Cryptographic Sequencer to hack your way in).
 * Arkham North: inside the office to the right of the Batmobile (required the Explosive Gel to blow a hole in the top).
 * Arkham West: inside the small office to the left Medical Facility lift.
 * Botanical Gardens: inside the Glasshouse Generator room, high up and requiring an amplified cryptographic sequencer to open.
 * There's a 5th Riddler Map in the Warden's Office at the Arkham Mansion.

Arkham City Incident
See: Riddler Thugs

Riddler abandoned the use of Riddler maps, as Batman had managed to defeat him by using them in Batman: Arkham Asylum. He instead hired thugs and sent them undercover to different gangs so they could hide his trophies without suspicion. However, Batman set his cowl to identify Nigma's known associates and interrogated them for information on where the trophies were hidden.

Arkham Knight Incident
Like in Arkham City, Riddler Thugs were used instead of maps.