Here's an example of inverted syntax: Normal syntax: Jane ate a cake. Inverted syntax: A cake Jane ate.
I think that the second line probably has inverted syntax, since you can re-write it as shown below: Sentence given (inverted): How lonely rings the echo of my feet! Sentence re-ordered (normal): The echo of my feet rings lonely.
EDIT: I think I made a mistake above ^ I believe its actually line three, which can be re-ordered to read: I gaze at those windows which frown
