what was the biggest empire in the world?

For most of the U.N.'s 103 member nations, opposition to colonialism is like being against sin—and generates almost as many proposals for reform. In a General Assembly debate on the "liquidation" of the West's remaining colonies, more than 50 nations in four weeks argued over resolutions that ranged from Russia's strident demand that 1962 be the year for total elimination of colonialism to a Nigerian proposal to set a nine-year deadline for Africa-wide independence. The resolution that was finally adopted last week largely reflected the moderation and good sense of onetime colonies in Africa and Asia. Over repeated Communist-bloc attempts to mine it for propaganda, the program adopted by a 97-0 vote in the General Assembly sets no specific date, instead demands independence "without further delay" for the 55 million dependent people still ruled by the Western powers, and sets up a 17-member special committee to check on their progress.The U.S. forcefully reminded the U.N. of the 200 million people who are seldom mentioned in debates on colonialism: the subjects of Communist imperialism. The West has liberated over 800 million dependent people since 1945. By contrast, declared the U.S.'s Adlai Stevenson in an eleven-page memo to delegates, the Communist empire is: 1) "the largest colonial empire which has ever existed in all history,''*2) "the only imperial system which is not liquidating itself but is still trying energetically to expand in all directions," 3) "one of the most cruel and oppressive ever devised." Warned Stevenson: "Because the world cannot long remain half slave and half free, the United States expects that the United Nations will focus its attention as carefully on the 'colonialism' of the Soviet Union as it does on that of Portugal or any other nation. For if the Soviet Union comes to believe it can enforce a double standard in the world with complete impunity, no country in the world will be safe.

The Roman Empire ;)

China empire.