World

The international super power that has claimed a third of the world, while still expanding. It is a monarchy where complete authority is given to the monarch, they rule over their country (or in this case, area or empire) and its citizens without any laws or opposition towards them. Britannia itself resides on (our) North American continent, and has already colonized the whole South American continent. Area 11
When it was formerly known as Japan, it was a country rich in resources, specifically it's energy source Sakuradite. It was invaded by Britannia in 2010 for the Sakuradite resource. With Britannia's newly designed weapons, "Knightmares", the Japanese had no chance, and was colonized within a month. Japan had its new name, "Area Eleven" with their people known was "Elevens". The Elevens had their homes taken away from them and were cast into the ghettos. They are greatly discriminated against, with many restrictions placed upon them. China
China, or in the series, the Chinese Federation, doesn't play much of a role in the series. Schneizel occasionally mentioned 'negotiating with the Chinese' and in episode 20, the Chinese are supporters of the Japanese rebellion. China's wealth is equally distributed in the series, which reflects our China's communist government. Other Countries
Other countries make an appearance in Code Geass, but do not play a large role. For example, in Stage 05, the episodes begins with Cornelia and her army attacking a country in the Middle East. The character Laksharta is from India, and the EU, possibly the European Union, supports equal rights for its people.
Locations
Ashford AcademyA school residing in Area 11. It is the school that Lelouch and all his friends attend. They have a high school and a middle school (and possible more) divisions. All students live on campus in dormitories, with the exception of Lelouch and Nunnally, who live in the Student Council quarters. No other schools have been mentioned in the series, so it is possibly the only school in Area 11.