Definition, Please?

Alright...so my post title is more inspired by a spelling bee than photography....

Definition is a great tool to adding pop to your photography. I tend to think of it as "intelligent contrast" and use it particularly on subjects that have texture I want emphasized: roads, buildings, sand, and so on.

An example from a 35mm scan of the Pantheon in Rome. Today, the structure is shadowed by the surrounding buildings. I wanted to capture the feeling of a more supreme stature of the building, looming over the square, being larger than life...how I imagine it was like 2000+ years ago. The original shot:

Pantheon: Original shot

Ok. Not bad. But the columns and frieze lack punch. And with the overcast sky, the Pantheon wasn't jumping out. By adding definition to the entire frame (save the triangle of sky in the upper right), the columns and engraved text started to pop. I actually added two passes of definition, the second being about half strength of the first, really pushing the textures of the stone. The adjusted shot:

Pantheon: Adjusted shot with liberal definition added

Yeah...really pushed the stone texture :)  And yes, I decided to give the sky a touch of blue using a color monochrome adjustment. It's not perfect, and I'm still not happy with the halo, but it's better than the muted gray.