Start off by taking time to have a look at write anything you can see in the picture. Don't worry about sentences yet, just write the things (nouns) you can see, and any good adjectives for the place.
Okay now let's trying using our other senses with our imagination. What else do you think you could sense?
What could you hear in this place?
What could you smell in this place?
What could you feel?
Could you taste anything different?
Get 5 or 6 strips of paper. On each strip write a descriptive sentence about the new setting that Jemmy has been taken to. Think of our 5 senses to help you come up with ideas.
Once you have several descriptive sentences written, try and put them into an order to make a whole desriptive poem, putting the words "The city" between each line, for example:
Towering grey stone reaching high up to the sky,
Where have all the colours gone? Why is it all so dull?
Once you've worked out the order of your poem, either stick your paper strip sentences down in their order, or rewrite it in your neatest writing.