The Underground Rivers of Athens

Beneath the streets of central Athens flow several ancient rivers covered over during the city's rapid expansion. The most famous is the Eridanos, running beneath Monastiraki Square, but urban legend claims there is a second, unmapped network of tunnels — not ancient waterways, but hand-carved passages created by secret societies during the Ottoman occupation.

Workers excavating for Athens Metro Line 2 in the 1990s reportedly broke into a sealed tunnel near Syntagma Station that matched no official plan. According to workers interviewed by a journalist, the tunnel ran north toward Omonia Square and contained iron brackets mounted on the walls at regular intervals. The discovery was officially classified as "a drainage culvert" and sealed within 48 hours.