In order to achieve this trophy, you have to open the map on every unique location. It's sufficient to just open the map, you don't have to play the mission all over again.
There is a really good video guide from MaxedGamers which shows all spots; all credits belong to him.
It's recommended to do this while your normal playthrough, but you can re-access every mission through the van within the hideout.
In case you like checklists, here is the one I made.
Prologue: Paris
- I Smell A Rat: Map as Sly
- I Smell A Rat: Map as Bentley
Episode 1: Feudal Japan
- Hideout: Map
- Breakout: Map
- Sushi House Start Up: Map
- Somethings Fishy: Map
- Pretty in Pinker: Map
- Spiked Sushi: Map
- Altitude Sickness: Map at the beginning (Emperor's Palace)
- Altitude Sickness: Map during the fight (Face to Face)
- Open World: Map
Episode 2: Wild West
- Hideout: Map
- Jailhouse Blues: Map
- Cooper for Hire: Map
- Saloon Bug: Map
- Blind Date: Map
- Jail Break: Map
- Operation Gold Digger: Map
- Open World: Map
Episode 3: Ice Age
- Hideout: Map
- Unexpected Ties: Map
- Going Up: Map
- Getting Stronger: Map
- Ice Ice Bentley: Map
- Operation Jurassic Thievery: Map at the beginning
- Operation Jurassic Thievery: Map during the fight
- Open World: Map
Episode 4: Medieval England
- Hideout: Map
- Juggling Act: Map
- Mechanical Menace: Map
- Short Supply: Map as Murray
- Short Supply: Map after Entering the Shoemaker
- Short Supply: Map as Galleth (1st floor)
- Short Supply: Map as Galleth (2nd floor)
- Shell Shocked Heart: Map
- Operation Mousetrap: Map
- Open World: Map
Episode 5: Ancient Arabia
- Hideout: Map
- Rug Rats: Map at the first area
- Rug Rats: Map at the underground
- Rug Rats: Map at the top of the tower
- Copy Cats: Map
- Heavy Metal Meltdown: Map
- All Rolled Up: Map
- Open World: Map (general)
- Open World: Map within the Lazy Trunk Spa & Lounge
Epilogue: Paris
- Hideout: Map
- Deja Vu All Over Again: Map
If you need a complete list of all maps and masks within this game, you can look at my solution for