There are no indicators when you're near. Remember to action ("Discover") the wall inscriptions—don't just look at them. Each new character can revisit the symbols and get credit for the challenge.
This wiki is currently incomplete. Please help complete it, if you can.
Windshear Waste (1)
Enter Claptrap's Place, in the room/closet on the right, next to the bank (YT)
Southern Shelf (2)
(south) In the building with the elevator in the south, take the elevator, turn right on the porch to access the roof, drop down to the ledge with the chest (YT)
(north) On the second floor of the ship (after all the toilet containers and section with no floor), when walking up the light gray incline, jump into the alcove on the left and follow the platforms around whence you came (YT)
Southern Shelf - Bay (2)
(southwest) On the starboard side of the (first) shipwrecked boat (YT)
(east) In the easternmost part of the bandit fort, head north under the two pylons in the snow and look up and behind you upon reaching the wall (YT)
Three Horns - Divide (3)
(south) In the Windbreak Camp (where you retrieve the power core), check behind the hut to the left near the cliff (YT)
(southwest) About-face from the bottom entrance to the Valley—it's on the back of that billboard (climb the support beams) (img, YT)
(southwest) Head north from the SW Catch-a-Ride into the bandit settlement—stay to the right towards the back, go up the stairs to the snowy platform (passing the gas tank) and look behind the arched unit on your left (YT)
In Scooter's, head towards the fence behind him, and turn right towards the tires pile—it's in the corner (YT)
Exiting Moxxi's western entrance, before descending the stairs, take a sharp look to the left. It'll be in the corner, on the wall. (YT)
Heading towards Marcus (the ammunition guy), turn left down the alley before the health vending machine—it's to the left of the disposal unit (YT)
To the left of that alley's entrance, climb the bench and the scaffolding leftwards, cross past the "GUNS" sign, and follow the rooftop—it's on the level above the black market (Crazy Earl's) on the door (YT)
Exit the second floor of Roland's house and follow the rooftops to the right—it's on the rooftops behind the newsstand in Sanctuary's town center (YT)
Three Horns - Valley (3)
(south/middle) Approach the fort next to the Catch-a-Ride (the fort that leads to Southpaw Steam) and follow the rocks to the left surrounding the fort, climb over the pipes—it's on the wall to your right (YT)
(south) In the far south, drive around the small lake to the drilling rig and shack housing two badasses—it's inside the shack (YT)
(northeast) In the honk-to-enter bandit fort, turn left by the drawbridge controls, follow the snow ridge around and it'll be on your left (YT)
Southpaw Steam & Power (3)
In the first room with the big pit, jump down and and look in the cranny to the right near the ladder (YT)
After the first assassin and climbing the stairs to the next area, you can see it on the wall to your right near the spinning gear and bottomless pit—see it on the wall when facing the bright light and fan. Use the rails to jump up top. (YT)
In a section on the left just before Assassin Reethe's entrance (the third), there is a large spinning gear—jump atop it and onto the small structure with steam vents and it's on the wall (YT)
Frostburn Canyon (2)
(NE) When entering the first cave, follow the side trail on the left—it's up a level on the floor (YT)
(NW) In the area with the ice pit and ladder, drop down and it's on the right wall (YT)
The Dust (3)
(SW) In the open pipe area ("Moonshiner's Camp"), climb atop the shacks on the left to check the pipe's lid (YT)
(middle) Look under the westernmost helipad (crouch and crawl) in the settlement ("Goost's Roost") in the middle of the map (YT)
(SE) In the northern bump of the loop in the SE, look behind the wall on its NE side (YT)
Bloodshot Stronghold (2)
(west) In the area with the prison cells where you meet Roland in person for the first time, take ladder to the second level, follow it around to where three pipes form a platform, take that to the control room, it's on the wall opposite the controls (YT)
(middle) On the Splinter Group quest, right before you ring their doorbell (in the room with the red triple eye), the symbol is on the wall to your right (YT)
Bloodshot Ramparts (1)
(middle) Halfway through the level, a girder forms the hypotenuse of a right triangle, look under the ramp before it to the left (YT)
Friendship Gulag (1)
(north) In the top-middle of the map, check behind the crate on the left (YT, YT)
Tundra Express (2)
(north) Behind a building near a drilling unit in plain sight, next to a fork in the train tracks. (YT)
(SE) Climb atop the Varkid Ranch Observatory using the cave entrance and stairs in its own SE (YT)
End of the Line (1)
Halfway through the map look on the side of the bridge near the remains of the train (YT)
Sanctuary Hole (1)
Heading north in the first bend of the S-shaped section, look beneath the stairs on the wall around the corner (YT)
Caustic Caverns (2)
(NW) Near the crystalisks in the NW corner, go to the nub that reaches the farthest north on the map (you can go around the right) (YT)
(S) Heading full circle towards the entrance again, you'll enter a room with vending machines, an ECHO recorder, and a ladder. Towards the top of the ladder, look behind you—there is a passage off of the ladder's shaft (YT)
Fink's Slaughterhouse (1)
See that big Slaughterhouse sign? Look behind a nearby pillar to its right (YT)
The Fridge (2)
Upon entering, it's on the roof of the building to your right—climb the rocks on the far side of the building to get there (YT)
Still towards the beginning on the frozen floor, look left to see a wall with yellow graffiti on the outside—check behind it (YT)
The Highlands (1)
(E) In the Hyperion area in the east, follow the natural path to the end (near the double rainbow and go around the outside of the circular "silo" (YT)
Wildlife Exploitation Preserve (2)
(SW) On the docked ship in the Harbor, wait for the crane to lower, then ride it to the end—the symbol is on a wall on the roof of that building (YT)
(SE) Follow the highway all the way to its terminus—it's on the road's ground (YT)
Natural Selection Annex (1)
The open Hyperian container you can walkthrough on the right side of the Annex, walkthrough it looking up.
Holy Spirits Bar (1)
Bathroom, in the bottom-left corner of the posters (YT, YT)
Thousand Cuts (2)
(W) In Brick's complex, it's on the back of the building near the rocks/cliffs (YT)
In view of the red Hyperion gate, hop to the shack atop the pillars and look inside (YT)
Near the westernmost vending machine, there is a walkway over water on the lower level. Crouch in the water—it's on the walkway's underside (YT)
(SE) In the construction area near the crane, look for the hole that goes several levels down. It's beneath the lowermost platform on the right (YT)
in gunslinger's corner, turn off the electrical fuse box and take the elevator to the top, go past the electrified fence that should be off now and jump from the trunk of the car to the roof and continue forward stopping between the blue and green rooftops. Look down.
the second vault symbol is also on a roof, follow the tracks down main street to the stairs leading up on the left side of the tracks. Follow the stairs to the top of this building, jump on top the lockers and after climbing up to this roof, jump to the next roof. The Rx drugs sign is where you should be. Put the sign to you're back and jump to the top of this building then walk down the other side and look down.
The Bunker (1)
1.The cult of the vault is along the ring under the left side of the waterfall. Face the waterfall and jump off the right side of the ring that has no security rail, there are rocks underneath and you can jump back to the ring after.
Eridium Blight (3)
In the Eridium Extraction Plant on the outside of the building on the left, in the back right before the last container.
Just before entering Hero's Pass, on the left is a Hyperion door with a yellow ammo chest on the left side of the door. Walk around the right side, the vault symbol is on this tiny building.
While debating over killing yourself, at Handsome Jacks' request, might as well get something out of the deal; this vault symbol you will see as you cross the walking bridge from Mount Hell to Lover's Leap. It's on a container on the left as you run toward your doom. Farthest point North other than the volcano.
Ore Chasm (1)
the hidden vault symbol is underneath the elevator you take to get back to the top so bring a friend to kill you because you have to push the button then stand underneath it while it crushes you.
Sawtooth Cauldron (2)
(W) Go all the way to that small area furthest west. It's in the cargo freight on the left inner wall.
Take the elevator all the way to the top of Buzzards Nest. push the elevator button to send it back down, then quickly back out and get on top of the elevator. the symbol will be on the 8th scaffolding beam down on the left side if facing the back of the elevator where the button is.
Arid Nexus-Boneyard (2)
(SW) when you first enter, turn to the left and walk the borderline toward the south, around the eridium pond. From there it's right in front of you on the turret tower.
(E) there's a ramp on the east side of the eridium pipeline, just before the catch-a-ride that farthest east. Walk up the ramp and run towards the part of the pipe you run a vehicle into and you'll walk into the second vault symbol.
Hero's Pass (2)
Upon entering go to the vending machines and walk between the vending machine and the container, look left on the wall.
After the cargo ship is knocked into the lava. Crossing a bridge the cargo ship is on your left side, at the end you crouch under a support strut(there is a cash box sitting on a box here) move onto the rock. Make a 180 turn and you will see the Vault symbol on the support strut under the bridge.
Vault of the Warrior (1)
After your elevator ride down, facing the direction you're suppose to go in, turn right and notice the boxes and the scaffold surrounding the elevator, explore...
Terramorphous Peak (2)
on a cliff next to the elevator below the first bridge you cross after respawning there is a corpse and a paintbucket next to it.
Under the platform you drop down from to enter the arena with Terramorphous. Stand over where Terramorphous errupts from the ground after being summoned and you might be knocked up close enough to reach it. You'll be airborne so be quick.
Mr. Torgue's Campaign of Carnage
The following symbols are found in areas in the second campaign DLC: Mr. Torgue's Campaign of Carnage
Badass Crater of Badassitude (4)
In a hut on the top of a building on the west-side entrance to the Arena. You can get there by climbing the ladder behind the highway advertisement board, turning around and jumping to it.
Just north/northwest of the previous symbol. Jump back down off the top of the building behind the sign where you climbed up. Continue onward between the buildings and the valley wall until the end.
At the very end of one of the raised highway sections. Get there from the ramp at the end of the road on the far west of the map (it leads around towards the north.)
Behind a building just west of the entrance to The Beatdown.
The Beatdown (2)
In the northeast corner (where you emerged from Pyro Pete's Bar after the campaign mission), follow the road south until the opening to courtyard with the water tower just off to the west. The symbol is on the far side, in plain sight on the wall.
From the southeast corner of the map, move west past the highway on-ramp from the north side. About 3/4 the way down the hill is a balcony. Jump to it. The symbol in on the building wall.
In the northeast corner of the outer ring (about 2 o'clock), up high on the wall. Climb the boxes to get there.
At the northernmost point of the outer ring is a ladder down. The symbol in on the wall behind the ladder at the bottom.
Southern Raceway (2)
In the northwest corner alcove, climb to the top of the buildings in the middle of the area. The symbol is on the west side of the hut with the antennae on it at the top.
In the northern-most central alcove (the one where you pull the lever.). It's in a hut at the very end of the alcove.
In the far west by Torgue Housing (near switch one from the story mission here), make your way to the top of the iron ramps. The symbol is on the side of a foundry building in the south-west corner, just follow the path behind the turret.
In the south-east region, just past the buzzard fighting ring and up the ladder on the east wall before Flyboy's lair. Jump onto a bus with a ramp on it's roof in the middle of the area and take the ramp to the elevated hut. The symbol is on the side of the hut.
Starting from the entrance to The Tower (Flyboy's buzzard tower lair), turn left, and you'll see a set of stairs. Walk down these stairs to the trash-heap looking area, then continue to the south side of the trash. Turn to face SW. The vault symbol is on that wall of the tower foundation.
Captain Scarlett and Her Pirate's Booty
The following symbols are found in areas in the first campaign DLC: Captain Scarlett and Her Pirate's Booty.
Head east on the Oasis Docks. About halfway down there's a wall on the right side. The symbol is on the back of the wall. (YT)
Head to Coral Island Camp (where you find the whiskey for the Fire Water quest). Go around the right side of the building and it will be on the wall. (YT)
Go to the wreck of the Kronus on the east side of the map. The symbol is on the outside hull of the east side of the ship. (YT)
You must complete the DLC's main story to enter this area. Exit the Leviathan's lair. Go into the shack directly in front of you. The symbol is on the wall to your left. (YT)
On the top deck of Captain Scarlett's pirate ship go around to the left hand side near the back. (YT)
Go to Rusty Corridor on the east side of the map. Following the edge of the cliff head south west. A wall will be in your way with a post to the right, go around it. Jump on top of the metal object then on top of the building. The symbol will be on the wall to your right. (YT)
Go to The Dish in the south east corner of the map. Follow the path south west that curves around the mountain. The symbol is on a wall behind a rare chest. (YT)
Hayter's Folly (2)
After defeating Grendel follow the exit out of his cave. At the end of the exit turn around and it will be on the left wall. (YT)
After you've found the vending machines, head into the hidden lair. At the top of the cliff just at the entrance look down and you'll see many cargo containers. Jump down to the two that are parallel to each other, the vault symbol will be on the side of one. (YT)
The Rustyards (2)
Go west into town from the start. On your left you will see a tugboat. Climb the stairs on the next building, walk around to the back of the building and head back east behind the tugboat. The symbol will be on a metal wall to your left. (YT)
Go to Maroonie's Clipper to the north. Walk east halfway the length of the ship. The symbol will be on the wall to your right. You will need to jump on some rooftops to reach it. (YT)
Washburn Refinery (2)
Right before you reach the 3rd poly-kryten there's a room that has stairs going downwards into a small area. The symbol is on the wall in that area. (YT)
In the room immediately after P3RV-E on the north wall, underneath the open hatch in the middle of the wall.(YT)
Magnys Lighthouse (2)
After crossing a hanging bridge you will turn right and go up a hill with train tracks. The house right in front with an antenna on the roof has a symbol on its back wall. (YT)
Go to the topmost level. Go around the back of the house to the right of the lighthouse. The symbol is on the base of the lighthouse where it meets the house. (YT)
The Leviathan's Lair (1)
When you are facing the exit of the lair, take the tunnel to your right. The side passage on the right has a metal wall blocking it. The symbol is near the roof on the wall to the right. (YT)
I can't tell you all the locations, and there is no indicator to let you know if you're close to one, but here are the locations of the ones we know.
There is one in Windshear Waste:
When you first enter Claptrap's Place, there is a closet to the right of the fireplace which releases deactivated claptraps when the door opens. The back wall of this closet has the symbol.
There are five hidden in Sanctuary:
On the floor in the corner under the stairs of Scooter's garage, behind some tires.
In an alley by Marcus's gun shop, behind and partially obscured by the dumpster there.
On a wall outside Moxxxi's joint. The wall is on the left if you leave the bar through the exit that faces Scooter's garage, and the symbol is small compared to the other symbols.
This and the next one require jumping on the rooftops. This one is located on the door on the balcony above the Black Market (where you buy BDUs with Eridium). To get up there, head toward Marcus's sign. There is a bench near an awning there, and if you stand on the bench you are able to jump onto the awning and from there over to the rooftop. Then simply climb over to the balcony.
This is on the roof behind the This Just In news stand in the center of town. The symbol is on the flat part of the roof by some boxes and safes. There is a stack of tires on the way to Rolands house, Jump from these to the awning, and up onto the roof, and across the street toward the This Just In stand.