The story
Welcome to the Rua da Alfândega, one of the oldest and most storied streets in Porto. As you stand before the imposing granite walls of the Casa do Infante, you are breathing in the salty air of the Douro River, just a few steps away. This building, with its heavy wooden doors and sturdy medieval silhouette, is famous for being the birthplace of Prince Henry the Navigator in 1394.
He was the man who launched Portugal’s Age of Discovery, but today, we are going to look even further back than the medieval explorers. We are going deeper into the soil of Porto, beneath the very floorboards of the Prince’s house. For centuries, this building served as the Royal Custom House and the Mint.
It was the center of Porto’s wealth and commerce. But during excavations in the 1990s, archeologists discovered that this site was a place of importance long before the Portuguese crown claimed it. Deep in the foundations, they found the remains of a luxurious Roman villa dating back to the 4th and 5th centuries AD.
Imagine the scene nearly two thousand years ago. Where you now see the gray stone of the medieval city, there once stood a grand residence belonging to a wealthy Roman official or a merchant. The centerpiece of this discovery is the Roman mosaic, a stunning floor that has survived the weight of empires.
As you look at these intricate patterns, notice the precision of the tesserae—the tiny cubes of stone and glass. The colors are earthy and warm: shades of terracotta red, creamy white, and deep ochre. These geometric motifs were not just decoration; they were a status symbol, signaling that Porto—or Portus Cale, as it was then known—was already a sophisticated hub of the Roman Empire.
The presence of this mosaic tells us that the Ribeira district has been the beating heart of the city’s economy for almost two millennia. This wasn't a humble home; it was a palace of trade. The Romans were drawn here for the same reason the Portuguese kings were: the river.
They used the Douro to transport wine, minerals, and salted fish. Standing here, you are standing at a literal crossroads of time. Above you is the 14th-century birthplace of a prince who changed the world's maps.
Below you is the 4th-century floor of a Roman citizen who helped build the foundations of European commerce. Take a moment to appreciate the silence of the stones. In the cool darkness of the basement, these mosaics remain a vibrant link to our ancient ancestors, proving that while the names of the buildings change, the spirit of Porto as a gateway to the world remains eternal.
When you leave, carry that sense of history with you as you walk the cobblestones toward the river.