The architecture of the Capitol is brutal, futuristic and imposing - its effect is to evoke a sense of stately majesty, authority and power.
The design of the set is made up of concrete structures and takes its inspiration from both communist and 1930's Germany Third Reich design/architecture . The buildings are large, concrete forms. The people of the Capitol look frivolous, so the set design needed to look intimidating and frightening. The open spaces (such as where the parade happens) are meant to invoke a sense of power.
In contrast to the Capitol, District 12 is very much an impoverished area. It was filmed at an old mill complex with workers’ housing. It was chosen as the buildings looked abandoned and in disrepair. This gives the impression that the characters live in squalor.
The set design for the arena is a beautiful forest. This highlights the irony of the situation - where children are killing each other. For the Capitol viewers, it is a lush and 'natural' setting, but atrocities take place here. There is a contrast of the horror and the beauty.
The cornucopia (pictured above on the right) is where the 74th Hunger Games begins.
The definition of cornucopia:
Think about how this part of the set design also highlights the irony of the tributes' situation.