1) The ocean covers about 71% of the Earth's surface and contains roughly 97% of the planet's water.

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

3) A newborn kangaroo is about 1 inch (2.5 centimeters) long and weighs less than a gram.

4) The Sydney Opera House, situated in Sydney, Australia, is an iconic architectural masterpiece and a UNESCO World Heritage site. Its unique design, resembling sailboats or shells, has made it one of the most recognized and photographed landmarks in the world.