Slaves were allowed to gather each Sunday in Congo Square, an old slave market in Louis Armstrong Park, to drum and practise their music.

BBC: New Orleans outside of the French Quarter

Precious metals, fabrics, weaponry and horses were all traded here, as well as humans -- Dyflin had the biggest slave market in Europe following the fall of the Roman Empire.

BBC: Dublin's Viking heritage

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.

CNN: From Samba to carnival: Brazil's thriving African culture

It's not supposed to be a slave market.

FORBES: Mad Hatchery Syndrome

It explains that the Americas were not the only world market for slave labor in the 15th and 16th centuries.

WSJ: Human Transactions | Spirits of the Passage | Frazier History Museum | By Mark Yost