This adjustment was made in Lab mode - I actually cheated and used CurveMeister from the RGB colour space (and you could use EasyCurves).
These are my curves...
The L channel curve has increased contrast by moving the left end in
(I set the Shadow point to the left of the main stairs)
and then wiggled a bit to improve the contrast in the distant.
The a and b curves are 'standard' Lab Saturation adjustments.
This method was the quickest and easiest of all the Curve adjustments and gave a pretty good result.