Stand in the alcove betwen the wall and the pillar. Perform the Chimney Jump to reach the handhold on the pillar.

Traverse to the left around the corner and jump to grab the handhold of the other pillar. Shimmy around the right hand corner and jump up to grab the handhold above.

Then jump to grab the architrave running along the wall behind you.

Traverse all the way to the right...

... and jump back to grab the handhold of the third pillar.

Shimmy to the right around the two corners and jump up to grab the ledge. Jump to grab the ledge on the left and continue to the left.

At the end, jump up to grab the ledge above and traverse to the right; pull up.