1) The Great Wall of China is a UNESCO World Heritage site and one of the most iconic man-made structures in the world. It stretches over 21,196 kilometers (13,171 miles) and was constructed to protect the Chinese empire from invasions during ancient times.

2) The construction of the Great Wall of China began in the 7th century BC and was completed over several centuries, spanning thousands of miles.

3) The Great Rift Valley is a geological feature that stretches over 6,000 kilometers (3,700 miles) from Lebanon to Mozambique. It is known for its diverse landscapes, including deep lakes, volcanic mountains, and fertile valleys, and is considered a significant site for the study of Earth's tectonic activity.

4) The fingerprints of koalas are so similar to humans that they have been mistaken at crime scenes.