Make a trip to the past in the streets of Ouro Preto, this historic city has amazing "Mineira" cuisine, amazing barroco churches and the wondeful architecture of it's golden years of Colonial Brazil, make sure to visit Gold Mines (the best one is located at the Passagem de Mariana)
I really liked the monument and the square behind it where's the map of the discoveries. It's easy to take some good pictures with beautiful background too!
Great place to visit. I recommend to buy the Classic Pass online (at least one day in advance). Explore the gardens, palace (audio guide included) and Gloriette :)