Why was the city of Potosi Bolivia built at such a high elevation?

Potosi, Bolivia is not actually located at a high altitude. It is situated at an elevation of around 2,950 meters (9,680 ft) above sea level, which is significant but not exceptionally high for a city in the Andes. Many other cities and towns in the Andes are situated at much higher elevations. For example, the city of La Paz, which is located about 600 kilometers (370 mi) northwest of Potosi, has an elevation of 3,650 meters (11,975 ft).