There are 12 treasure map locations and (obviously) 12 solution locations.
Location: Landsuther Mines
Map is next to a coffin inside the lift on the way down.
You need to go down in to the hole and ride the lift up to access it.
Solution: Lookout Tower
Behind the Thor Statue in The Lake of The Nine on the hidden beach next to the Jötnar Shrine on the. Next to Thor's foot.
Location: Fáfnir's Sroreroom
Grab it during Sindri's Favour "Fáfnir's Hoard".
There is a stone pedestal for the keystone. There is a map nearby.
At the entrance to Peak Pass, turn to find the location by the edge of the cliff.
Location: Forgotten Caverns
Not far from the gate to King's Hollow, there is a Mystic Gateway, between these is a cave with Wolves (one is fairly difficult at low level). There is a chest in here and next to it is the map.
Solution: Northri Stronghold
Best found during the "Family Business" favour, once the water wheel is activated and you can move further in to the Stronghold (first set of gates), there is a climbing section above the boat dock, climb that to find the solution.
Location: Witch's Basement
You can only access this after obtaining the both sets arrows for Boy.
Just before the Chamber of Odin, there is a room to the east, the map is in there.
You need to create the bridges to the Nornir Chest and near there is an electrical puzzle required in order to get to the chamber.
Solution: River Pass
Climb the well out of the Witch's basement. Head towards the Turtle and near some small pile of rocks (just off the rock path) is the solution
Location: Northri Stronghold
During "Family Business" you come across a traveller when you
. Nearby (where he entered the map), you'll find weak boards that lead under the boat. The map is inside.
Solution: Njörd's Oarsman
Dock at Mason's Channel on the left side of the Oarsman. Climb the cliff near Sindri's shop until a passway to the right opens up. Follow that to the statue, the soultion is down that path.
Location: Lookout Tower
Best found before the water drops the second time in Lake of the Nine. Park the boat at the dock, the map is nearby, to the right.
Between the lore marker and the gate during the Favour "The Imprisonment of Otr".
Location: Iron Cove
The easiest map to find in the game. Dock at the southern beach and just ahead by some barrells is the map
Solution: Buri's Storeroom
Depending on when you go for this, there is a fairly difficult Traveller on this island, make sure you level up a bit before you go for this. There are loose boards by the Draugr on the western side. Knock these down after the fight to get to the solution.
Location: Helheim Tower Beach
On the beach where the dock to Helheim tower rests. Head towards the Oarsman, off to the left of the dock is the map.
Solution: Light Elf Outpost
Go around the island to pass under a high level dock. Climb down the nearby chain to find the solution.
Location: Völunder Mines
After dealing with the Soul Eater and revenent follow the path right to get to the map
Solution: Cliffs of the Raven
By the corpse of the Troll at the back of the map by the spirit shrine.
Directly in front of corpse on the side of the shrine, you'll find tbe treasure.
Location: Stone Falls
At the first water drop, you can get this by leaving your boat and turning right to find it easily.
At the second water drop, you have to climb all the way to the top to find it in the same loaction.
Solution: Isle of Death
On the very top of the island is a shipwreck. Underneath is the treasure
Location: Mountain Summit
On your second visit, you'll find this just before the fight with the Ancient, the map is on the main path of the story.
Solution: Council of the Valkyries
It is in the throne room circle, near the middle of the map.
Location: Ruins of the Ancients
Kill the Soul Destroyer and on the right hand side is the map.
Solution: Fáfnir's Storeroom
When you reach the fight in the middle of the wooded area, before passing through the door, the treasure are just in front of them, pick them up and continue your journey.