To build the Alexandria shield you need to collect 3 parts which are localized to the following locations:

Part 1: Barrel Piece - Localised in the first room AFTER opening the main gate
- Resting against some junk by the police car
- By the stop sign on the corner of the road
- Resting against a concrete barrier near the generator trailer

Part 2: Spikes - Localised in the PaP zone
- Sitting on top of some white barrels in front of the garage by PaP
- Sitting on top of barrels near the container by PaP
- On top of a wooden crate down on the lake dock

Part 3: Handle - Localised in the farming area
- At the end of the path in between the corn crops
- Against the wall, left of the entrance to the doublke tap building
- On the ground against a sack of hay to the right side of the double tap building (near the side entrance to the building)

Buildable Bench can be found inside the basement of the large apartment complex next to PaP