Cities

[fanakz]

Chewing gum stained streets
are the city's freckles - I absolutely love this line, very endearing. Brings relevance to the reader
Our manifest idiosyncrasies. - I do not think this flows very well. It's also a stretch to try and make a sound metaphor out of it. 
Like the bright lights I would change "bright" lights, it's usually assumed a light is bright unless otherwise stated. You can use a more moving word, if you are trying to paint a picture. For example, "Like the [flickering] lights" 
which blemish the dark Earth. I would omit "dark" here. Also, since you chose the verb blemish, I would try to add more to the freckle image you began with.  "Which blemish our [long-faced] earth"
Humanity's beacons,
that countering the crawl
of dark uniformity:. I would prefer to end the poem here. It would become more powerful.  
In pairs, on motorways I don't know why, I can't make this line flow well when I am readinig it. 
illuminating intention and I like the alliteration and how it refers to the lights with "illumination." 
extinguishing the humdrum.

Or maybe it's just litter and light pollution. I see what you are trying to do here. It's a good concept; however, I think it takes away from the poem. I agree with Achebe.