Chung-nan-hai

To keep the “congress” proceedings secret, the observers said, the “deputies” picked up from “districts” and “units” on China mainland all gathered at Chung-nan-hai, a district where Mao Tse-tung usually resides. They went to the “People’s Hall” through a tunnel. After the “congress”, they came out through the same underground passage. Foreigners, including reporters living in Peiping could see the “People’s Hall” lit up at night during the meeting, but found no buses and sedans parked around the "hall". The truth was not bared to the world until after the regime itself issued the news on the "congress."

Source: wiktionary

When the Chairman, Chiang Ch'ing, and some leading comrades and their troops descended upon Peking in March 1949 and took possession of its center point, the Imperial City, they appropriated for their own use the western section bounded by the central and southern lakes called Chung-nan-hai (literally, Central and Southern Sea).

Source: wiktionary

On the east bank of the lake in Chung-nan-hai stood an exquisite two-story building in the European style.

Source: wiktionary