1) The world's largest particle accelerator, the Large Hadron Collider, is located near Geneva, Switzerland, and spans a circumference of 17 miles (27 kilometers).

2) The global push for COVID-19 vaccination campaigns has been a significant focus, with the development and distribution of vaccines to combat the spread of the virus and protect public health.

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

4) The Southern Ocean surrounds Antarctica and is the coldest and least-visited ocean.