I had not heard of this before, so I figured it was worth sharing. In ancient Greece there was a guy called Polycrates, and he managed to:

• Build a harbour wall to protect his city and fleet which is said to run into 35m of water and have a total length of 400m, thus easily making it the biggest breakwater in the world

• Build a tunnel nearly a mile long, eight feet wide and eight feet high, driven clean through the base of a hill nine hundred feet in height. Amazingly, they started tunnelling from both ends, and met in the middle.... precisely.

For the complete story follow the link below...