This is one of the first sights that greet visitors and a compelling one at that. A wall of arches arranged side by side and one row stacked on top of another rises 95 feet, making for a very dramatic picture. It towers over the hill town of Segovia. Constructed around the 1st century AD to supply water to the Roman military stationed on the hill from 15 km away, it was built by stacking more than 25000 blocks of granite without the help of mortar, and at more than 800 metres in length, it is indeed a feat of dextrous Roman engineering. While standing underneath gives a sense of being dwarfed, walking on the top gives unparalleled panoramic views of the city and the countryside.