The inhabitants of modern Rome still are the remains of aqueducts built by the ancient: solidly built Roman slaves plumbing facilities.
Don't you have to say about the knowledge of the Roman engineers in charge of these works; they clearly were not enough familiar with the basics of physics. Take a look at the attached picture, reproduced from paintings of the German Museum in Munich.
Water buildings of ancient Rome in their original form.
You see the Roman aqueduct was built not in the earth, and above it, on a high stone pillars. Why this was done? Isn't it easier to lay in the land of the pipe, as is done now? Of course, it's easier, but Roman engineers of the time had a very vague idea of the law of communicating vessels. They feared that in reservoirs connected by a very long pipe, the water will not install on the same level. If the pipes are laid in the ground, following the slope of the soil, in some parts of the water have to flow upwards, and now the Romans were afraid that the water didn't flow. Therefore, they usually gave the water pipes of uniform slope down all the way (and this was often required either to conduct the water to bypass or to build high arched supporting). One of the Roman pipes, Aqua, Marcia, has a length of 100 km, while the direct distance between its ends half. Fifty kilometers masonry had to make because of ignorance of elementary law of physics!