Beneath the streets of Lisbon’s historic Baixa district lies one of the city’s lesser-known yet fascinating landmarks – the Galerias Romanas da Rua da Prata. What makes them truly unique is the fact that for most of the year, they remain submerged under water and are only accessible on rare occasions. It’s a place that combines history, archaeology, and a generous dose of mystery.
What Galerias Romanas are?
Beneath the center of Lisbon lies a remarkable archaeological treasure. The Galerias Romanas da Rua da Prata are the remains of Roman urban infrastructure from the time when Lisbon was known as Olisipo. The entire structure is what’s known as a cryptoporticus — a system of underground corridors and arched galleries that, in ancient times, served as support foundations for buildings constructed above them. These types of structures were especially useful in cities built on uneven terrain, as they helped stabilize the architecture and allowed for the leveling of building surfaces.
The galleries are dated to the 1st century BCE / 1st century CE, meaning they were built during the reign of Emperor Augustus and represent one of the oldest examples of Roman architecture preserved in Lisbon. Interestingly, according to archaeological research, part of the underground structure may also have served as a cistern—a water reservoir, locally known as the Conservas de Água da Rua da Prata. This function was made possible due to specific hydrological conditions—the galleries are partially flooded, which means they remain underwater for most of the year.
The galleries are dated to the 1st century BCE / 1st century CE, meaning they were built during the reign of Emperor Augustus and represent one of the oldest examples of Roman architecture preserved in Lisbon. Interestingly, according to archaeological research, part of the underground structure may also have served as a cistern—a water reservoir, locally known as the Conservas de Água da Rua da Prata. This function was made possible due to specific hydrological conditions—the galleries are partially flooded, which means they remain underwater for most of the year.
