Things to do in Beijing

The four central districts are located within or just beyond Ring Road Two. This is the location of the old walled city of Beijing and is where you will find most of the sights and also a good deal of sleeping, eating and drinking and entertainment options. The districts are:

Xicheng District (西城区; Xīchéngqū)
covering the north western part of the central city area to just beyond ring two in the west and up to ring three to the north. Includes Beihai Park, the Houhai area, Beijing Zoo and National Concert Hall

Dongcheng District (东城区; Dōngchéngqū)
covering the north eastern part of the central city area approximately up to ring three to the north and ring two to the east. Includes the Forbidden City, Tiananmen Square and Beijing Central Station

Xuanwu District (宣武区; Xuānwǔqū)
covering the south western part of the central city area to just beyond ring two to the west and up to ring two to the south

Chongwen District (崇文区; Chóngwénqū)
covering the south eastern part of the central city area to just beyond ring two to the south and up to ring two to the east. Includes the Temple of Heaven

source: http://wikitravel.org/en/Beijing