The Prophet's Tomb - Escape from the Collapsing Ruins

After Lara's confrontation with the Trinity soldiers, there are still 2 bad guys left behind. Quickly shoot them from the partial cover of the tomb. If you can steady your aim enough for a headshot, you'll receive bonus XP, but don't worry too much about this. Just kill both of them...

...

...and run forward to where they were standing. Jump across the gap in the floor and continue on.

Here the game explains how to sprint by pressing in on the left stick as you push it forward, or by holding Shift on the keyboard along with the regular movement controls. As you approach another Trinity soldier...

...a huge chunk of rock falls on top of him. Turn left to avoid it.

Sprint forward, jump at the edge to grab the horizontal bar, and swing across...

...to grab the far ledge. If Lara slips, press Interact at the prompt to hang on. Pull up...

...and keep running/sprinting around the corner to the right.

As you enter this hallway, the floor collapses, and Lara slides into the room below.

Continue forward, jump across a gap in the floor.

Then run up the angled pillar and scramble up the column ahead. (Click here to see the weirdness at the top of this screenshot close up.)

The column tilts to the left as you climb on top of it.

Continue sprinting forward and jump to grab the next square column in your path. Pull up, move forward, and jump to grab the doorsill ahead. Pull up...

...and continue sprinting toward the light as the passageway crumbles around you.

Take a running jump across the wide gap in the floor, waiting until Lara is right at the edge before you press the Jump button then holding it for more air time. If you make it, run through the doorway to safety...and the end of the level.