Structure

A descriptive compostion about a place or building should consist of: 

A) An intoduction in which you identify it, give its exact location and state the reason for choosing it. 

B) A main body in which you describe the main aspects of the place or building in detail.

C) A conclusion in which you mention your feelings and your final thoughts about the place or give a recommendation. 

* Introduction 
    
    Paragraph 1: set the scene (name and location of the place/building, reason for choosing the place/building). 

* Main Body

   Paragraph 2, 3: overall look and particular deatails (place: sights, facilities, free-time activities building: first look and specific details). 

* Conclusion 
   
  Feelings and final thoughts about the place/building and/or a recommendation. 


- This link gives you a better explanation about how you should write your composition. 

http://www.slideshare.net/aponce4/writing-describing-places#btnNext