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 word "computer" contains three vowels: O, U, and E.

3) The word "table" contains two vowels: A and E.

4) The word "piano" contains three vowels: I, A, and O.