3. Aqueduct of Segovia
Image Source: Holly Hayes
Going back to 50 A.D., this ancient project is all the more impressive considering the fact that they lacked the modern construction equipment that does so much of the heavy lifting today. Located in Segovia, Spain, this massive project includes 167 arches as part of its structure, and was able to transport water some 11 miles from the Fuente Fria River to the city. It is constructed using about 24,000 granite blocks which do not have the benefit of being held in place by mortar.
