Lara immediately discovers the 'Broken Tunnel' base camp at the start of this area. [RELIC - #1 BRONZE COINS (BRONZE CHINESE COIN)] can be found next to the tree nearby this camp, and there's also some [HANDGUN AMMO] closeby. You can find a [GPS CACHE] next to the truck.
All collectibles in the Base Approach area.
As you proceed through the hall, Lara hears some guards. There are plenty of them up ahead, but a stealth approach is definitely possible by avoiding the searchlight (the guy controlling it also controls a turret, so it's a wise move to sneak past this part anyway). [100 XP].
Kill the first guard by approaching him from the back and choking him. Hide behind the sandbags with [ARROWS x2] next to them, then look how the searchlight moves around the area in a counterclockwise fashion. As soon as it shines on (or actually slightly right of) the sandbags you're hiding behind, move to the left and choke the guard on the left, then hide behind the barrels. You can now kill the guard to your right with an arrow headshot, followed by the welder near the building (but only when the searchlight is looking away.
Enter the building and stealth kill the welder inside. Slowly sneak upstairs and shoot the guard at the searchlight in the head while still standing in the hall. Slightly curve around the corner to spot another guard; dispatch him with yet another headshot. He's not the last; sneak over the walkway until you spot two final guards in the concrete building to the right. One of the guards moves away for a few seconds and then returns. It may be a little tricky to shoot him in the head as he moves away, but this is the best stealth approach. The other can be easily dispatched after this.
Now that you've killed all guards in this area, search the place for the following items and collectibles:
• Before entering the main building, move to the far right/east around the concrete tower to find a [PLANT] and some [HANDGUN AMMO].
• It's possible to climb the low part of this concrete tower (from the main open area) to find [HANDGUN AMMO].
• You can find [ARROWS x2] on the ground floor of the building near the entrance.
• [RELIC - #2 BRONZE COINS (BRONZE JAPANESE COIN)] can be found on the first floor. Head upstairs and go immediately around the corner. It's not too far away from the burning barrel.
• There are also some [ARROWS] at the top of the stairs on the first floor.
• You can also find [ARROWS] next to the searchlight.
• At the end of the first floor walkway, leap over to the concrete tower to find [ARROWS] next to the searchlight, and an [XP BOX] by going around the corner. A [GPS CACHE] can also be found nearby.
• Move to the top of this tower by scrambling up the wall. At the end you'll find some [HANDGUN AMMO] and a rope leading straight to the next area.