World Bulletin / News Desk

The worn paving stones discovered under a thick layer of modern concrete in Rio de Janeiro don't look like much at first. But it was here that some million slaves from Africa took their first steps in Brazil.

Next week, the UN cultural body UNESCO will consider whether to award what's known as Valongo Wharf world heritage status, winning protection as a site of global importance.

The wharf, or what remains of it, would join sites like the Taj Mahal in India and the ruined Inca city of Machu Picchu. UNESCO, which is meeting between July 2-12 in Krakow, Poland, already chose Rio de Janeiro as a heritage site in 2012, recognizing the city's unique combination of landscapes between mountains and the sea.

For Valongo, the honor would make it a twin with Ile de Goree, a small island in Dakar harbor that was chosen in 1978 as the emblem of the departure points for slaves from west Africa on their way to the Americas.

Now on the other side of the Atlantic from Senegal, across the grim route known as the "middle passage," the stones of Valongo Wharf commemorate the slaves' arrival.