St. Francis' Folly - Atlas Key and "I Am No Heracles" Achievement/Trophy

The entrance to the Atlas Room and the gorilla (21) inside are covered in the main walkthrough.

The "I Am No Heracles" achievement/trophy is tricky. The goal is to enter the trapped hallway ahead, trigger a boulder trap, and climb onto a safe ledge before the boulder comes to a stop at the other end of the hallway. Here's the strategy that worked for me:

First, visualize where you're headed. You can spot the safe alcove through the barred window.

Or, stand on the pressure pad with the Omega symbol to open the gate.

Then use Photo Mode (F3 on keyboard, L3 + R3 on controllers; i.e., click both analog stick buttons at the same time) to scout ahead. The safe ledge is on the left, directly opposite the last section of bars.

Now stand on the pressure pad and save the game. When Lara steps through, the gate closes.

Turn right and run forward along the right side of the passageway. When you reach the middle section of barred window, the huge boulder at the top starts to roll down the ramp.

Keep running, and as you approach the last section of barred window, veer left and hold Action. Don't jump, but continue to hold Forward/Up + Action as you run into the wall.

Lara should pull up onto the safe ledge. If you do this quickly enough, the boulder will miss her...

...and you'll unlock the achievement/trophy.

Once the boulder lands, the gate re-opens, but don't leave yet. Climb onto the long ledge above on the left and go to the far end.

Pick up the ATLAS KEY (13). Drop down from the ledge. Hop down into the pit where the boulder landed and pick up a small medi pack (14). Then climb out of the pit and exit back to the main area.

[St. Francis' Walkthrough]