During the 17th and 18th century, Brazil faced one of most important and rich periods on its history. By that time, explorers found enormous mines of gold and precious gems in the mountains in the interior of the country, in a region called Minas Gerais (general mines). In this region, the richness of the mines created spectacular cities with enchanting architecture and art. After the exhaustion of these mines and the beginning of a new economic cycle in the coffee farms, cities like Ouro Preto, Mariana, Tiradentes and Diamantina were virtually abandoned, leaving a spectacular treasure behind. Ouro Preto is certainly the most important city of that period and was declared a World Heritage site by UNESCO.