The two tunnels are located at km 31 of the Athens-Sounio road and have always been a point on the road network that required special attention from drivers due to their dangerousness. In the past, drivers honked every time they passed through the tunnel. Some still honk today. The first tunnel (now heading towards Athens) was built in 1954, the second was only added in 1980 and was Karamanlis's heartfelt wish. Konstantinos G. Karamanlis was a Greek politician who served two terms as Prime Minister (1955-1963 and 1974-1980) and twice as President of the Hellenic Republic (1980-1985, 1990-1995) and left his mark on the period after Greece's independence. The tunnels are very short, about 7 meters long, but are located on a curve.
The old tunnel is also steeped in history due to an assassination attempt that took place there. The tunnels became famous after the assassination attempt on George Papadopoulos by Alekos Panagoulis on August 13, 1968, which failed because the improvised explosive device exploded a few seconds after the dictator passed through the tunnel.