In the colonial era the Portuguese colonizing the Brazilian interior discovered gold, gems and later diamonds, starting a Brazilian gold rush and attracting new settlers. In 1697, the Portuguese used enslaved Africans to build the Estrada Real, the "royal road" that would connect the ports on the Atlantic to the mineral-rich region of Minas Gerais. More than 400,000 Portuguese and half a million African slaves abandoned the sugar plantations and towns in the northeast coast to go to the gold region to mine and by 1725 half the population of Brazil was living in southeastern Brazil. In the 18th century officially 850 tons of gold were sent to Portugal but other gold remained in the colony to adorn churches. The gold cycle left its mark in several towns such as Mariana, Diamantina, Tiradentes, São João del Rei and mostly Ouro Preto, for centuries capital of Minas Gerais. Declared a World Heritage Site by UNESCO in 1980, in the eighteenth century was the largest city in Brazil and one of the most populous in America. The relative isolation from Europe helped the people of Minas Gerais to develop their own style of art which became known as Barroco Mineiro, with richly decorated churches. The most important artist of this time was Antônio Francisco Lisboa, known as Aleijadinho. His sculptural and architectural work is one of the most refined artistic expressions outside Europe at that time, a rich colonial heritage and colonial art. In addition to art and architecture the towns of Minas Gerais were home to an important musical activity helped by printed copies of European music, many foreign musicians travelled here favoring the origin of a local school with considerable sophistication. During the 18th century, mining exploration was controlled by the Portuguese crown which imposed heavy taxes (one fifth of all gold). Several rebellions were attempted by the colonists but the most important was the Inconfidencia, started in 1789 by intellectuals and young officers and inspired by the French and American Enlightenment ideals. The conspiracy failed and the most famous of them, Joaquim José da Silva Xavier, known as Tiradentes, was hanged becoming a national martyr of Brazil. In the economic history of Brazil, Minas Gerais plays a pivotal role in shifting the economic axis from the Brazilian northeast based on sugarcaneto the southeast of the country, which still remains the major economic center.