Lima, Peru's capital and largest city, still uses a system of ancient canals to provide water across the desert city.

The city today has a population of almost 9 million people. But to supply this sprawling metropolis with water, Peruvians rely on canals that were built before the first Europeans ever set foot on the American continent.

These four structures, constructed by the Wari, Ichma and Inca civilizations, are more than 2,000 years old. Experts continue to preserve a number of these canals, the Spanish news agency EFE reported.

Four canals help irrigate 732 parks

One of the canals, known as Surco, uses water from the Rímac River to irrigate 12 of Lima's 43 city districts in a 19-mile stretch, providing sustenance to greenery in 732 parks, the newswire detailed. But to journalist Para Lizarzaburu, the structure is not only a practical tool, but also illustrates the feats of engineering achieved by pre-Hispanic cultures in the Americas.

"To construct an irrigation system implies knowledge; it is not simply opening up a ditch in order to make the river cross a part of the desert. That is why it is very certain that each of the four canals is oriented in a different manner," Lizarzaburu marveled.

The canals suggest that the Incas and other cultures possessed remarkable topographical analysis skills, as the canals have no tendency to cause flooding.

'Thank those who lived here 2,000 years ago'

Interestingly enough, a lot of people in Lima have never heard of the ancient structures. 

"The residents of Lima do not even know that they live in a desert, that they have to thank those who lived in this area some 2,000 years ago and who began to build a system of canals and thus allowed this city to survive," the investigator noted.

"Lima's canals are a pre-Hispanic institution that continues to serve a city that today - more than ever - depends on the work of (long-passed) citizens who transformed the desert in valleys and who today help better the lives of 9 million," he added.