1) The eye of a cyclone is a region of calm, relatively clear skies and light winds at the center of the storm.

2) The oldest known musical instrument is a flute made from a bird bone, estimated to be around 43,000 years old.

3) The Federal Reserve System, often referred to as the Fed, is the central banking system of the United States.

4) The Machu Picchu archaeological site, located in Peru, is an ancient Incan citadel situated high in the Andes Mountains. It is recognized as a UNESCO World Heritage site and attracts visitors from around the world who come to marvel at its remarkable architecture and scenic surroundings.