Another discovery of recent years is the remains of a squalid slave cemetery in the courtyard of a home in central Rio de Janeiro.
Renaldo Tavares, an archeologist who has been studying the discovery, said: "These are human remains mixed in with the garbage from the city. It shows how society in the 19th century treated slaves.
"Bones, pieces of ceramic, bits from construction, tiles, animal remains, bits of food, society threw all sorts of things in here. Slaves were considered garbage by society."
Ana de la Merced Guimaraes, the homeowner who discovered the bones in her courtyard, said: "When we started a reform in our house, we found all these bones. We thought it was a family grave, but there was so much we thought maybe it had been a serial killer.
"But then we calmed down and talked about it and called a lawyer and the police. And he said don't worry, we aren't going to accuse you, it's probably something very old.
"A neighbor told us, a long time ago, your street was a slave cemetery."
Brazil's third city Salvador, in Bahia state, northeast Brazil, has some of the strongest links to Africa.
Salvador was the first colonial capital of Brazil and its central district, Pelourinho, now a UNESCO world heritage site, was the New World's first slave market from 1553, according to UNESCO.