Pittsburgh - Alone and Forsaken
Artifact #29: Siphon Hose
Bill will give this to Joel at the end of the previous chapter.
Comic #1: Force Carrier
This is automatically in your possession upon starting the chapter.
Artifact #30: Tourists Manifest
Once you enter the hunters' garage, look for the overturned tool cabinet in a corner of the room. This lies on top of it.
Training Manual #2: Health Splinting
Once you head up the stairs, make a right to find a room with several mattresses on the floor. Near the centre of the room is a rack. You'll find this manual on the bottom shelf.
Artifact #31: Ambush Map
Before exiting the building through the brown door, head down the hall through grey one. Turn around upon entering to find this pinned to the wall.
Comic #2: Termination Shock
Once you drop to the ground from the hunters' building, you'll be near a bus. Step aboard and make a left to find this on the ground in the rear.
Artifact #32: Lost Hill Note
When you reach the checkpoint, hop over the right sandbag pile (the one near the graffiti that Ellie points out). Check in the booth here for a well hidden artifact.
Artifact #33: Traitors Flyer
After moving through the turnstile, there will be a large covered area in front of you. Head toward it and turn around to find this plastered to the wall.
Firefly Pendant #11
On the far end of the large bookstore is an alley. Head down it to find a pendant behind an overturned shelf.
Artifact #34: Abandon Zone Note
On the opposite side of the bookstore is another alley. Head down it, enter the building, and make a right. Mantle the first ledge and turn left to find this item sitting on a desk.
Artifact #35: Applicant Checklist
Before heading to the top floor of the bookstore, head to the front of the store and check behind the staircase there. You'll find another artifact underneath.
Artifact #36: Lost Areas Map
Use the staircase near the centre of the store to reach the top floor of the building, and make a left. In this corner is a locked door you can open with a shiv. Do so to find lots of supplies and this artifact.
Artifact #37: Mother's Letter
Proceed until a short cut scene with hunters taking a plank occurs. Make an immediate left to spot a door marked with a red "X." Use a shiv to open this door, and you'll find an artifact atop a chair directly inside.
Artifact #38: Stash Note
When you swim through the green muck to help Ellie reach the plank, hang left toward this submerge storage unit. Swim through it (you'll have to eventually) to enter a flooded a building with a staircase in the rear. Head up, and follow the room as it wraps around to find an artifact sitting on a desk.
Pittsburgh - Hotel Lobby
Artifact #39: Note to Staff
After using the ladder to bypass the broken staircase, turn right. You can shimmy along the edges here to reach an open suitcase in front of some double doors. This note lies inside that suitcase.
Training Manual #3: Shiv Reinforcement
With the Note to Staff in hand, you can open the safe in the lobby. Drop to the ground floor and look behind the check in desk for said safe. Another manual lies inside.
Artifact #40: Hotel Keycard
You'll find this in the area where you fight the Bloater. After taking out all the infected, head to the upper floor via the stairwell. Follow the rooms as they wrap around to the right to find a security room. In here, this artifact rests next to a stack of televisions. (This unlocks your exit door, so you'll need to obtain it anyway.)
Comic #3: Accretion
Once Ellie saves you, climb the ladder and enter the next room. Exit via the left door to spot a bar across a gap. You can shimmy over there, where you'll find another comic atop a table.
Firefly Pendant #12
Soon after, you'll drop down to a lower floor. As you turn down the hallway, there will be two restroom entrances on your left. Enter the second and head to the corner stall to find this on the ground near the toilet.
Training Manual #4: Melee Knots
Just past the elevators on the same side of the hallway is a desk with a red chair. This manual sits on that desk.
Pittsburgh - Financial District
Artifact #41: Fireflies Note
Battle your way through the plaza where Joel gives Ellie the rifle, and head forward. On the right will be a building labelled Don Fiocchi Subs. Enter and head to the back room with the blood smear to find this item on the floor.
Artifact #42: Final Attack Note
After ascending the staircase and taking out the two patrolling hunters, take a right before dropping to street level. In this small office room, an artifact lies beneath a desk.
Artifact #43: Mob Attack Note
As you come around a corner street, there will be enemies on a ledge of the Delta Direct building. Head inside that building via the doorway under the sign and take the stairs. Once on the top floor, check behind the large desk for a hidden artifact.
Artifact #44: Truck Note
Before leaving the area, you'll pass by the Ration Depot. Enter and move straight ahead past the first desk to find an artifact sitting atop a second desk.
Pittsburgh - Escape the City
Training Manual #5: Molotov Construction
While following Henry out of the apartment, stop in the kitchen to grab this manual off the counter.
Comic #4: Deep Phase
On your way down the stairs, open the locked door with a shiv. Make a left to find a kids' bedroom, where you'll find a comic on a desk chair.
Firefly Pendant #13
After taking out some hunters on the rooftop, you'll cross a plank into another building. Before heading into Henry's safehouse on the right, make a left to enter the bathroom. This sits atop a toilet in the corner stall.
Artifact #45: Trial Note
Once inside Henry's safehouse, head straight ahead to enter a boardroom. Make a left to find this on the ground in the corner.