The Tunnel of Eupalinos in Samos is an incredible feat of ancient engineering which boasts UNESCO World Heritage status. 

Built in the 6th century BC, this underground aqueduct was designed to supply fresh water to the ancient city of Samos. 

The tunnel stretches for approximately 1 kilometer and was constructed through solid rock.
The engineering genius behind the tunnel was Eupalinos, a Greek engineer commissioned by Polycrates, the tyrant of Samos at the time.  

This feat of coordination and precision engineering was unprecedented in its time.
The tunnel, which has stood the test of time, showcases the advanced engineering skills of the ancient Greeks. It is a testament to their ingenuity and determination. 

Today, the Tunnel of Eupalinos in Samos continues to be a marvel of ancient architecture and a must-visit for those interested in the rich history of Greece.