The town began as a mission. In the 1750s a Jesuit priest, Father Roque Hunderfund, worked his way up the Xingu and asked Xipaia and Kuruaya men to guide him toward the Volta Grande, the enormous horseshoe bend the river makes before it turns north. Near the mouth of the Panelas stream they settled on a site, and the Tavaquara mission took root there. The Marques de Pombal shut the Jesuits out of the Portuguese colonies not long after, and the place went quiet for the better part of a century until a priest reopened the overland trail in 1841. On 2 April 1883 the village was raised to town status and renamed Altamira, under the patronage of a Colonel Francisco Gayoso, who had a road cut from the lower to the middle Xingu using enslaved African labour. Long before any of this, people had lived along these rivers speaking languages including Kuben-Kran-Ken, a Je tongue of the Kayapo group that no one speaks now.

Brazil's military government sold Amazon colonisation with a slogan: a land without people, for people without land. It was wrong in the first half and cruel in the second. Landless families from the drought-stricken northeast were trucked in along the new Trans-Amazonian Highway, whose eastern section opened on 27 August 1972, and settled on lots measured out beside a road that turned to red soup for months of every year. Many of the plots failed. Many of the settlers stayed anyway, because there was nowhere else to go, and Altamira absorbed them. That is roughly the state the town was in when the 1979 film Bye Bye Brasil sent its travelling circus here as the last stop on the map - a hot, muddy frontier town at the far end of a road that had promised more than it delivered.

Then came the dam. Construction on Belo Monte began in 2010 at the Volta Grande downstream, and to make room for the reservoir the consortium emptied the parts of Altamira that sat lowest on the water. About a quarter of the city's urban population was moved, along with ribeirinho families whose houses had stood on stilts at the river's edge for generations. They went into six collective urban resettlements on the outskirts - RUCs officially, ruquis in local speech - identical small masonry houses laid out in grids, too far from the centre to walk to and too far from the Xingu to fish from. For people who had lived by putting a net in the water in the morning, the loss was not sentimental. It was economic and total. Estimates of how many people the project displaced in all vary widely, from about twenty thousand by International Rivers' count to fifty thousand by the reckoning of the local group Xingu Vivo, and the range itself tells you how little care went into counting.

During peak construction between 2012 and 2015, nearly thirty thousand workers were on the Belo Monte site, and Altamira's population swelled past 150,000 from the 99,075 recorded at the 2010 census. Rents tripled. Shopping centres appeared. So did the other things that arrive with a sudden all-male payroll and no institutions to match it: in the early 2000s Altamira's homicide rate was around 11 per 100,000 residents, and by 2017 it had reached 135, one of the worst in Brazil. Then the payroll ended. The workers left, the rents stayed high, and the city was left with the infrastructure of a boom and the economy of a river town. The 2020 count put the municipality at 115,969. What Altamira gained in those years is real - a functioning airport, a regional hospital, an unusually dense network of Indigenous organisations and NGOs. What it paid is also real, and mostly went unrecorded.

Altamira covers 159,533 square kilometres, larger than any other municipality in Brazil and larger than 104 countries, at about 0.73 people per square kilometre. Nine of its ten districts are rural and separated from the seat by hundreds of kilometres of forest, dirt road and river. Most of that territory is not farm or pasture but protected area and Indigenous land: the Terra do Meio Ecological Station alone runs to 3,373,134 hectares, and the Altamira National Forest, Serra do Pardo National Park and the Nascentes da Serra do Cachimbo Biological Reserve all take a share. The inhabited part is compact, 109 metres above sea level and drenched by 1,844 millimetres of rain a year. Walk twenty minutes from the centre and the pavement runs out. What is on the other side of it is most of the municipality.