1) The Great Barrier Reef in Australia is the largest coral reef system in the world and is visible from space.

2) The Mona Lisa, painted by Leonardo da Vinci, is one of the most famous and valuable artworks in the world.

3) The first successful portable MP3 player, the Diamond Rio PMP300, was released in 1998 and could hold up to 60 minutes of music.

4) The ancient city of Athens, Greece, is often considered the birthplace of democracy, where citizens had a say in the decision-making process.