St. Francis' Folly - Secret #1

After getting rid of that pesky Frenchman, return to the movable block, on the left (north) side of the big room, and climb up on it. (First make sure you've pushed it as far as it goes toward the gorilla/switch room.)

Walk to the edge and take a standing jump to grab the taller stone block next to it and pull up.

Turn left, walk to the edge, hop back once, then take a running jump to grab the next pillar. Pull up.

Turn left, walk to the edge, and line Lara up facing the ledge in front of the doorway ahead.

Hop back and take another running jump to the ledge.

Now the actual secret: As you enter the room, there's an angled block that meets the floor on the left (A in the diagram). Stand Lara in the doorway facing this block, with her left foot on the line of tiny triangles that spans the doorway. (This is the red line in the diagram.) Walk forward as far as possible toward the angled block.

Use Look to check that Lara is facing the slope squarely.

Then hop back once. Lara should end up with her back against the side of the angled block behind her (B).

Hold Action. Press Jump + Forward, then release Forward, but continue to hold both Action and Jump. Lara will jump onto the angled block ahead (A), backflip off it, land on the angled block behind her (B)...

...automatically turn to face down the slope, and jump to grab the ledge above (C).

Continue holding Action but release Jump, then press Forward to pull up to the middle level.

Here you'll find 2 more angled blocks—a lower one on the left (D), a taller one on the right (E). Position Lara facing the middle of the lower block with her back against the higher block. Hold Action and press Jump + Forward to jump onto the lower block (D).

Release Forward while continuing to hold Jump and Action, and Lara will backflip onto the higher block (E)...

...then jump forward and grab the ledge above (F).

Pull up to the upper level. This is SECRET #1, which includes a large medi pack (1) and shotgun shells (2). Run across the break-away tile (27/51) in the corner (G) to shatter it for the "After Us the Deluge!" achievement/trophy, but don't fall through. It's a long way down. Instead, safety drop to the middle level from the same spot where you climbed up. Then hop/slide down to the floor.

[St. Francis' Walkthrough]