Q:

"Look at" vs "Look on"

I just got asked which sounds better, and I have no idea which one should be preferred:

"A closer look on how buildings are manufactured."

vs.

"A closer look at how buildings are manufactured."

Is there a difference, or personal preference, or which one should it be?

A:

EDIT: Thanks to FumbleFingers' ear, StoneyB's mind and Snailboat's eye I will "modify" my answer. Many thanks to all.
Only look at can be the acceptable choice in this instance. To look on is a verb, but in the sentence below it is used as a noun.

"a closer look at how buildings etc." 

(Original answer)
I think it's the word, closer, which forces me to prefer "at". We often use look at to mean to see something with attention, whereas look on can sometimes mean to consider, take into consideration. 

