Answer:
Hi! so the question states that you should write a letter to your friend about your city. Unfortunately I do not know where you live, but I will try my best to make an answer that you can use for any city!
I live in _insert city name_. - J'habite à _votre ville_.
My city is large, and beautiful. - Ma ville est grande et belle.
There are many large buildings. - Il y a beaucoup de grands bâtiments.
There is a luna park near my house. - Il y a un parc luna près de chez moi
There is a library near my house. We can get books there. - Il y a une bibliothèque près de chez moi. On peut y aller chercher des livres.
There is a park near my house. We can take a walk in the park. - Il y a un parc près de chez moi. Nous pouvons nous promener dans le parc.
In my city, there are many monuments we can visit. - Dans ma ville, il y a beaucoup de monuments que nous pouvons visiter.
if you want, you may also say:
In my city, there are many monuments such as _insert monument name_. - Dans ma ville, il y a beaucoup de monuments tels que _.
In the city center there is great pizza! - Dans le centre-ville, il y a une excellente pizza!
or if you have any specialties in your country, you may say the dish name like this:
In the city center, there is an amazing dish called _. - Dans le centre-ville, il y a un plat traditionnel étonnant appelé _.
Hopefully I gave you enough choices for your answer :)
have a great day!