Before Mount Everest was discovered, what was the highest mountain in the world?

The highest mountain in the world before the discovery of Mount Everest was still Mount Everest itself. The distinction lies in the human recognition and discovery of the mountain's height rather than its actual elevation. Mount Everest, located in the Himalayas on the border of Nepal and the Tibet Autonomous Region of China, has always been the tallest peak on Earth at an elevation of 8,848.86 meters (29,031.7 feet), even before it was identified and measured by people.

Thus, prior to its official discovery and subsequent measurement in the mid-19th century, Mount Everest existed with its towering height, but it was simply unknown to the wider world. This reflects an interesting aspect of human exploration and knowledge: geographical features can exist independent of our awareness, and in this case, the mountain's elevation was unchanged regardless of its recognition.