Potosí is one of the highest cities in the world at an astonishing 13,420 ft above sea level. Potosí lies at the foot of the Cerro de Potosí which is often referred to as the Cerro Rico meaning "rich mountain". It is called so as it is known to be "made of" silver ore that controls the city in many ways. Potosí was a major supplier of silver to the Spanish empire until the 18th century (Wikipedia) 

Potosí  is referenced in the poem Eighteen Hundred and Eleven, a Poem:

"Potosi hears it, as she digs the ore"

This line is very relevant given its extreme elevation and the city's reliance on the silver mountain that it lies under. The city's elevation allows them to hear the man's cries. The mentioning of the ore points toward the imperial usage of the town's silver, like the Spanish and British did frequently, which is relevant to the theme of the poem, imperialism/war.