1) The Eiffel Tower can be 15 cm taller during the summer due to thermal expansion.

2) The world's most expensive car is the Bugatti La Voiture Noire, which sold for over $18 million.

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

4) The sunflower is not a single flower but a cluster of small flowers arranged in a spiral pattern.