But as developers press ahead in the surroundings of the unearthed slave port — with futuristic projects like the Museum of Tomorrow, costing about $100 million and designed in the shape of a fish by the Spanish architect Santiago Calatrava — the frenzied overhaul is setting off a debate over whether Rio is neglecting its past in the all-consuming rush to build its future. 

“We’re finding archaeological sites of global importance, and probably far more extensive than what’s been excavated so far, but instead of prioritizing these discoveries our leaders are proceeding with their grotesque remaking of Rio,” said Sonia Rabello, a prominent legal scholar and former city councilwoman....

Scholars say the scale of the slave trade here was staggering. Brazil received about 4.9 million slaves through the Atlantic trade, while mainland North America imported about 389,000 during the same period, according to theTrans-Atlantic Slave Trade Database, a project at Emory University.