What the dam created, the region calls Mar Doce de Minas - the Sweet Sea of Minas. It is not a metaphor Brazilians use lightly. The reservoir covers 1,040 square kilometers, nearly nine times the size of Guanabara Bay beside Rio de Janeiro. Islands scatter across a surface that once was farmland and forest, river valley and falls. One of those islands became the Estação Ecológica de Pirapitinga, a protected refuge where the waters stop and the old cerrado begins again. From the shore of Três Marias itself, population 32,716, you can stand and see no opposite bank. The far side is simply horizon. Fishermen work the reservoir in small boats. Tourist lodges cluster along the eastern shore. The hydroelectric station, officially named Bernardo Mascarenhas, generates 396,000 kilowatts - a number that meant development and modernity in 1961, when Brazil was racing to build itself a future.

The dam rose in four years. Construction began in 1957 and finished in January 1961, a pace that was, by the standards of earthworks that size, almost impossible. Ten thousand workers moved earth in two shifts around the clock. The structure that emerged stretches 2,700 meters long and 75 meters high - one of the largest earth dams in the world. The speed came from one man's impatience. Juscelino Kubitschek, Brazil's president and a Minas Gerais native, had promised fifty years of progress in five. In those same years his crews were also raising Brasília from empty savanna, extending the BR-040 highway northward, and bridging the São Francisco. Três Marias was one project in a national rush. The workers who built it lived in company camps on the riverbank, eating in communal mess halls, earning wages that by the standards of the sertão were worth the separation from home. When the sluices closed and the water began to rise, some of them stayed to farm the new shoreline. Their descendants still live here.

Folklore fills the gaps official history leaves behind. The most beloved of the three origin stories tells of a couple who lived on the right bank of the São Francisco, long before hydroelectric dams existed in anyone's imagination. They had triplets - three girls, all named Maria. Word of the birth spread through the region; triplets were rare enough to become a local wonder. The waterfall near their home began to be called the Cascade of the Three Marias, and the name stuck long after the daughters, the story claims, drowned in the river. No birth certificate preserves their existence. No death record confirms their end. The tale persists because the place needed one. A competing version credits Orion - the constellation whose three belt stars hang visible year-round over central Brazil, three bright Marias watching the sertão night after night. A third, more prosaic explanation points to the three waterfalls themselves, now gone. Pick the story that suits your mood. Each is true in its way.

The BR-040 highway threads directly through Três Marias, carrying trucks and travelers between Belo Horizonte and Brasília. This is why the place exists in the form it does - not just a dam town but a crossroads, a stop on one of the most traveled federal routes in Brazil. The landscape around is high cerrado, the Brazilian savanna, rolling at around 550 meters above sea level, hot and semi-humid with an annual average of 22.5 degrees Celsius. Rice, sugarcane, corn, and soybeans grow on the outskirts. Cattle graze the natural pasture. The municipality is geographically vast at 2,763 square kilometers but demographically small, which leaves the horizon clean and the stars at night genuinely visible - which may be why the Orion explanation, once you have stood here in the dark, feels the most convincing of all.