Approach the edge of the ledge and jump to the sloped pillar.

As you slide down, do not press anything and Lara will land on the beam below. If she loses her balance, she will hang from the beam, so pull up. Walk to the other side of the beam and jump to grab the narrow ledge on the pillar. Traverse to the left around the corner and pull up to hug the wall. Jump forward to land on top of the next pillar.

Turn right and jump to the small square ledge, then to the next one. Jump to grab the narrow ledge on the pillar and...

... traverse to the right around the corner. Pull up to hug the wall and perform the Chimney Jump to grab the walkway above. Pull up.