Which empire is considered to be the largest in history?

The largest empire in history is generally considered to be the British Empire. At its height in the late 19th and early 20th centuries, it spanned approximately 13.01 million square miles and governed around a quarter of the world's population. The empire's vast territories included regions in Africa, Asia, the Americas, and Oceania, leading to the phrase, "the sun never sets on the British Empire."