Things You'll Need
Instructions
Advance your story to Chapter 5--Urban Warfare. This chapter that contains no rare artifacts holds the game's "Strange Relic."
Flee the military truck in the opening chase scene. Run and gun, aiming for the truck's grill while Drake sprints down the alley. Avoid getting stuck on boxes and other obstacles and the truck should explode after a few pulse-pounding seconds of chase.
Progress the chapter until a bus forms a roadblock in the middle of the street. The area just after the bus is your goal. Once you've climbed through the blown-out buildings on the left side of the street, clear the next area of enemies before you begin your relic hunt.
Search the upper-right corner of the map for an open manhole cover. Drop down into the sewers and you will find a flashing egg. Of all the hidden artifacts, the "Strange Relic" is actually one of the easiest to find.