1) The word "telephone" contains five vowels: E, E, O, E, and E.

2) The Iguazu Falls, located on the border between Argentina and Brazil, is a majestic waterfall system consisting of numerous cascades and islets. It is a UNESCO World Heritage site and one of the most impressive natural wonders in the world, attracting millions of visitors each year.

3) Mount Everest, located in the Himalayas, is the highest mountain on Earth, reaching a peak elevation of 29,032 feet (8,848 meters).

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