Souvenirs

[The Four-Eyed Cat]

Just wrote a comment and then my browser crashed, damn you, technology!

I love the poem you've written here. The imagery is strong and the first stanza vividly reminds me of the Vondelpark in Amsterdam. 
Correct me if i'm wrong, but my personal interpretation of this poem is a man witnessing the urban expansion consuming remnants of nature. 
I also feel there's a deeper underlying notion (due to the last sentence).

SOUVENIRS

Beyond my flat's double glazed glass,
I see a hazy midday scene:                                                - Creates a strong and great image. Good choice of words;
Flocks of tourists napping in grass,                                    A 'hazy midday' and 'double glazed' is a brilliant match.
The slow and subtle spread of shade,                                - Gives me a great picture of how the angle of the sun just changes throughout the day
Tall men with their sub-legal trade,                                     - The 'sub-legal trade' is one of the reasons why it reminds me of the Vondelpark
And on trees the emerging green.

I look with greater focus now,                                           - it's as if the protagonist already knows that he will reminisce this moment, thus preparing us
Upon this fading midday scene,                                       for the final stanza
As I begin to notice how
The spring cement's purity                                                - Not too fond of you using 'purity' twice. Also, I personally think cement is rather 'impure' 
Heightens the plumb logs purity,
Showing a forest that had been.

When I am archaic yet wise,                                             - Something feels off with 'archaic yet wise', i feel that 'yet' gives it a negative connotation.
I will still see this midday scene,                                      perhaps that was your intention, but personally i'd go with and, or just change the whole line
But never again through live eyes;
Never at all with the power                  
To sweeten a youth gone sour.                                         - Fantastic line, I think this might be the strongest one in the poem
Too much to take in at eighteen.