Photo: Thomas Gravanis

The Hidden Entrance to Hadrian’s Aqueduct

Photo: Thomas Gravanis

Under Kolonaki’s streets, a Roman aqueduct quietly connects ancient engineering, living rituals, and today’s Athens.

When was it built

Hadrian’s Aqueduct was constructed in the 2nd century AD, during the reign of Roman Emperor Hadrian, who ruled from 117 to 138 AD. It formed part of a wider building program that transformed Athens during the Roman period.

What's the story

A testament to Emperor Hadrian’s deep admiration for Athens and Greek culture, the aqueduct was designed to supply the city with fresh water for centuries. Stretching approximately 15 miles (25 km), it runs mostly underground, and was used to channel water to public baths and reservoirs intermittently from Roman rule to the 19th century. One of its most visible remnants today lies beneath Dexameni Square in Kolonaki — a name that literally means “reservoir.” Though no longer in active use, the aqueduct remains structurally intact and functional.

Why it's important

Hadrian’s Aqueduct highlights the advanced engineering of the Roman era and underscores Athens’s historical importance within the empire. Alongside landmarks like the Temple of Olympian Zeus, Hadrian’s Arch, and the Library of Hadrian, it reinforces the emperor’s lasting architectural and cultural legacy in the city. Today, it also plays a role in modern discussions about sustainability, as authorities plan to reuse it for non-potable water supply.

Must-see

Visit Dexameni Square, where everyday city life unfolds directly above the ancient water system. The discreet entrance to the cistern is housed in a simple 19th-century white building next to the open-air cinema. If you’re in Athens on January 6th, don’t miss the Epiphany celebration, when the local church lowers a cross into the cistern’s waters in a symbolic blessing — a rare moment when the site comes vividly to life.

Fun fact

Although it dates back nearly 2,000 years, Hadrian’s Aqueduct is considered Europe’s longest functional underground aqueduct — officials are planning to bring the Dexameni building back into use for cultural purposes, proving that ancient infrastructure can still serve modern Athens.

A discreet white 19th-century building in Dexameni Square marks the entrance to Hadrian’s ancient water system.

Photo: Thomas Gravanis

The alter-like tunnel entrance at the far end of the cistern leads into a 15-mile network carved beneath the city.

Photo: Thomas Gravanis

Light filters into the empty reservoir, highlighting centuries-old stonework once filled with flowing water.

Photo: Thomas Gravanis

Past and present meet at Dexameni, where ancient infrastructure survives in the heart of the city.

Photo: Thomas Gravanis

A rare glimpse into Athens’s underground history, where Roman engineering still stands the test of time.

Photo: Thomas Gravanis

An unassuming doorway opens onto one of Europe’s longest underground aqueducts.

Photo: Thomas Gravanis

The usually empty cistern reveals the scale of the engineering hidden under modern Athens.

Photo: Thomas Gravanis

Though no longer in active use, the aqueduct remains structurally intact and functional.

Photo: Thomas Gravanis

Eat & Drink

Eat & Drink

Eat & Drink

Eat & Drink

The Hidden Entrance to Hadrian’s Aqueduct

Under Kolonaki’s streets, a Roman aqueduct quietly connects ancient engineering, living rituals, and today’s Athens.