1) The Great Wall of China is not visible from space without aid, contrary to popular belief.

2) The French Revolution, which began in 1789, marked a major turning point in European history, leading to the overthrow of the monarchy and the rise of republicanism.

3) The abolition of slavery in the United States was officially proclaimed with the ratification of the 13th Amendment to the Constitution in 1865.

4) The Southern Ocean surrounds Antarctica and is the coldest and least-visited ocean.