Archaeologists from the University of Cambridge have unearthed a European Christian church on a Cabo Verde island, 500 km off the coast of West Africa - where the Portuguese established a stronghold to start the first commercial links with Africa.
This turned into a global trade in African slaves from the 16th century, in which Cabo Verde played a central part as a major trans-shipment centre.
This church is the oldest formal European colonial building yet discovered in sub-Saharan Africa, according to researchers.
The earliest remains of the church of Nossa Senhora da Conceicao date from around 1470, with a further larger construction dating from 1500.
Extensions and a re-cladding of the church with tiles imported from Lisbon have also been documented.
"We've managed to recover the entire footprint-plan of the church, including its vestry, side-chapel and porch, and it now presents a really striking monument," said Christopher Evans, director of Cambridge Archaeological Unit (CAU).
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"Evidently constructed around 1500, the most complicated portion is the east-end's chancel where the main altar stood," he said.
"This had been built as a free-standing structure prior to the church itself and is now the earliest known building on the islands," Evans explained.
During the excavation, several tombstones of local dignitaries were recovered.
One enormous stone found in the side chapel belonged to Fernao Fiel de Lugo, a slaver and the town's 'treasure holder' between 1542 and 1557.
"This excavation has revealed the tombs and graves of people that we only know from history books and always felt could be fiction," Cidade Velha's mayor, Manuel Monteiro de Pina, said.