"Segovia Aqueduct is a true feat of engineering, and a testament to the prowess and survival skills of the ancient Romans. Although it's undergone a few modifications over the centuries, it still retains its original structure from nearly 2,100 years ago. No tickets are required—you can just glimpse it from the outside. The lack of cement or mortar between the stones may leave you dumbfounded—if not wholly impressed." - Ramsey Qubein
Getty