The Mona Lisa is considered very valuable not only because Leonardo da Vinci painted it, but because of its seminal influence on the art world. Its mysteriously engaging smile and the details of the portrait makes it a milestone work in the world of art.

Alexander Graham Bell is credited with inventing the first practical telephone. His work on the design of the telephone started in earnest in 1874, and by March 10, 1876, Bell made his first successful call to his assistant, Mr. Watson.

The original lineup of AC/DC consisted of Angus Young, Malcolm Young, Dave Evans, Larry Van Kriedt, and Colin Burgess. The band was formed in Sydney in 1973.

Albert Einstein, the renowned German-born theoretical physicist, developed the theory of relativity, which fundamentally changed our understanding of space, time, gravity, and the relationship between energy and matter. His groundbreaking work laid the foundation for modern physics.

The Arab Spring began in Tunisia in December 2010 after a street vendor set himself on fire to protest the arbitrary seizing of his vegetable stand by police over failure to obtain a permit. His act sparked wider protests fueled by anger over government corruption, lack of political freedoms, and economic issues like high unemployment. The protests soon spread to other countries in the region.

"Cats" premiered in London in 1981 and on Broadway in 1982. It is based on T.S. Eliot's book "Old Possum's Book of Practical Cats." The show won numerous awards, including the Laurence Olivier Award and the Tony Award for Best Musical.

This famous paradoxical saying is attributed to Socrates. It embodies his approach of questioning everything and acknowledging the limits of human knowledge. Socrates taught by asking probing questions rather than proclaiming to have all the answers.

Sidney Poitier won the Academy Award for Best Actor in 1964 for his role in the film "Lilies of the Field". He was the first Black actor to win in this category. Poitier paved the way for other African American actors in Hollywood.

Angkor Wat, originally constructed as a Hindu temple dedicated to the god Vishnu, later became a Buddhist temple. It is located in Cambodia and covers an area of over 400 acres (1.6 square kilometers). It was built by the Khmer King Suryavarman II in the early 12th century.

The statue of David was completed by Michelangelo in 1504 and has been on display at the Galleria dell'Accademia in Florence, Italy, since 1873. The iconic sculpture is considered a masterpiece of Renaissance art.