But there's one part of de Souza's legacy that is seldom addressed. After arriving here in the late 1700s from Brazil, then a Portuguese colony, he became one of the biggest slave merchants in the history of the transatlantic slave trade.
In Benin, where the government plans to build two museums devoted to the slave trade in collaboration with the Smithsonian Institution, slavery is an embattled subject. It is raised in political debates, downplayed by the descendants of slave traders and deplored by the descendants of slaves.
At a time when Americans are again debating how slavery and the Civil War are memorialized, Benin and other West African nations are struggling to resolve their own legacies of complicity in the trade. Benin's conflict over slavery is particularly intense.
For over 200 years, powerful kings in what is now the country of Benin captured and sold slaves to Portuguese, French and British merchants. The slaves were usually men, women and children from rival tribes — gagged and jammed into boats bound for Brazil, Haiti and the United States.
The trade largely stopped by the end of the 19th century, but Benin never fully confronted what had happened. The kingdoms that captured and sold slaves still exist today as tribal networks, and so do the groups that were raided. The descendants of slave merchants, like the de Souza family, remain among the nation's most influential people, with a large degree of control over how Benin's history is portrayed.
In building the new museums, the country will have to decide how it will tell the story of its role in the slave trade. Is it finally ready, for example, to paint de Souza as the slave merchant that he was?
"The tensions are still there," said Ana Lucia Araujo, a professor of history at Howard University who has spent years researching Benin's role in the slave trade. "In the past, the country had a hard time telling the story of the victims of the slave trade. Instead, many initiatives commemorated those who enslaved them."
Unlike some African countries, Benin has publicly acknowledged — in broad terms — its role in the slave trade. In 1992, the country held an international conference sponsored by UNESCO, the U.N. cultural agency, that looked at where and how slaves were sold. In 1999, President Mathieu Kérékou visited a Baltimore church and fell to his knees during an apology to African Americans for Africa's role in the slave trade.
But what Benin failed to address was its painful internal divisions. Kérékou's apology to Americans meant little to citizens who still saw monuments to de Souza across this city. Even Ouidah's tour guides had grown frustrated.
"These people don't know the history. De Souza was the worst person, and he's still treated like a hero," said Remi Segonlou, who runs a small business showing visitors around the city.
The memory of slavery emerges here in large and small ways. In the 2016 presidential election, one candidate, Lionel Zinsou, angrily pointed out in a televised debate that his opponent, Patrice Talon, who is now president of Benin, was the descendant of slave merchants. In villages where people were abducted for the slave trade, families still ask reflexively when they hear a knock on the door whether the visitor is "a human being" or a slave raider.
"Our anger at the families who sold our ancestors will never go away until the end of the world," said Placide Ogoutade, a businessman in the town of Ketou, where thousands of people were seized and sold in the 18th and 19th centuries.
When his children were young, Ogoutade told them they were barred from marrying anyone who was a descendant of the country's slave merchants.
Some of Benin's foremost scholars are battling the country's unwillingness to interrogate its messy past.
"This is still a country divided between the families of the enslaved and the slave traders," said Olabiyi Babalola Joseph Yai, a professor of history and linguistics who taught for years at the University of Florida and worked for UNESCO in Paris before returning to his native Benin. "But the elite don't want to talk about what happened here."
The Smithsonian Institution has signed a memorandum of understanding to provide help with the new museums, although details have yet to be worked out, officials said. Benin's government has also appointed several scholars, including Yai, to ensure the accuracy and credibility of the exhibits in one of the museums, in the city of Allada, about 20 miles from Ouidah. But even Yai questions the authorities' willingness to address the facts.
"Is this about reconciliation, or is it just about attracting tourists? That's something we need to be vigilant about," he said.
There are several reasons Benin's history of slavery was papered over or misrepresented for so long. First, when Benin was a colony of France from 1904 to 1958, the French didn't want to draw attention to their own role in the African slave trade. Then, after Benin became independent, its leaders pushed for a sense of national, and even Pan-African, identity.
Since 1991, when Benin transitioned from a dictatorship to a democracy, the history of slavery has mostly been presented as a means of luring Western tourists.
"People here are trying to find work. They are trying to eat. They are surprised when they see tourists who come looking for their identity," said José Pliya, the president's adviser for tourism.
Pliya is directing the establishment of the two museums, one focusing on Ouidah's history, due to open next year and funded largely by the World Bank, and the other in Allada, which will more broadly investigate the country's role in the slave trade and is scheduled to open in 2020. The two sites are expected to cost $24 million in total.
The government is also planning to reconstruct the forts where slave merchants lived in Ouidah and the cells in which they kept their slaves.
The government acknowledges that if it wants to attract tourists, it will need to address concerns about whether Benin is whitewashing the actions of the slave trade's architects. Advisers to the president said he plans to rename the Place de Chacha square in Ouidah, said to have been an open-air auction site for slaves. Authorities have not yet decided on a new name.
"This is a very delicate subject," Pliya said.
Many members of the de Souza family are aghast at the idea.
"He was a man who helped modernize our nation," said Judicael de Souza, 43, noting his ancestor's role in expanding agricultural trade with Europe.
One member of the family, Martine de Souza, a tour guide, has urged the family for years to re-examine its history. "It's time we accept the reality," she said in an interview. But most others are cautious.
Late last year, the family appointed its new patriarch, or Chacha. He is a construction engineer named Moise de Souza who lives in a concrete apartment building with a poster-size picture of himself on the wall. He has light brown skin, a point of pride for a family that often boasts about its ties to colonialists.
In an interview, he acknowledged his ancestors' role in the slave trade.
"It is something that makes me feel bad. We know it's painful, and all I can do is apologize," he said.
Still, he worried that members of his family would be livid if he shared that sentiment publicly in Benin. He vehemently opposes any mention of de Souza as a slave merchant in the new Ouidah museum.
"It's the reputation of our family," he said. "We don't want to be known for this dirty thing."
In mid-January, he and dozens of other de Souza descendants made their yearly pilgrimage to the city of Abomey, the former capital of the kingdom of Dahomey, a major regional power in pre-colonial days. A modern-day king of Dahomey, Dédjalagni Agoli-Agbo, still presides, even though the title is now a largely ceremonial one.
The meeting had an extraordinary subtext. The kingdom of Dahomey had sold hundreds of thousands of slaves to merchants like Francisco de Souza. The ceremony was about celebrating a relationship between two families that was originally forged over slaves.
On that humid morning, Moise de Souza stepped out of an SUV wearing a gold-trimmed shawl and cap. He walked to the front of a dimly lighted meeting room, sweating in the heat. A group of American anthropology students, almost all of them white, had been allowed inside to watch.
Finally, the king arrived, surrounded by several wives wearing matching yellow-and-orange dresses. He shook de Souza's hand. Glasses of champagne were poured.
"This ceremony reminds us of the connection between Dahomey and de Souza," the king said, as a Beninese TV crew filmed.
"I wish good health, a long life and peace to the king," de Souza responded.
Slavery was never mentioned.
"It's a memory both families would prefer to forget," said the professor escorting the students, Timothy Landry of Trinity College in Connecticut.
When the event ended, the de Souza family poured out of the building.
They wore outfits of bright, traditional African fabrics. On some of the skirts and shawls, a white man's face had been printed, his eyebrows raised, his mustache curled.
In case he couldn't be identified, the man's name was printed in big letters.
"Francisco Félix de Souza."