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

2) The Russian Revolution in 1917 resulted in the overthrow of the monarchy and the establishment of a communist government under Vladimir Lenin.

3) The Treaty of Versailles, signed in 1919, officially ended World War I and imposed heavy penalties and reparations on Germany.

4) The tongue of a blue whale is so big that about 50 people could stand on it.