NAZCA LINES: ARE THEY A MYSTERY?

This article talks about the Nazca Lines. These one are a series of ancient geogliphs, that is, some drawings on the ground made by moving stones, which are located in the Peruvian desert, in an area of 500 square kilometres. In this area, we can find many figures in the shape of animals and plants, for example, a monkey, spider, cactus and many more.

Nowadays, there are many theories about their purpose. On the one hand, some people believe they are astronomical calendars or that they have a religious significance, or even, that the lines are landing strips for alien aircraft. On the other hand, there are different opinions about how they were made. From air hot balloons to aliens, although the most possible is that people used to tools and other ways methods to design straight lines and shapes.

In my opinion, it is very difficult to know how this phenomenon happened in Peru. However, I think the answer is easy but we have not found the solution yet. From my point of view, the most realistic explanation more real for me is that the ancient Nazca celebrated religious meetings or rituals for their gods. Because of this, they designed big shapes to show their gods. Nevertheless, the theory about landing strips for alien aircraft, currently, it is the single theory which is able to explain all about this phenomenon.

Without a doubt, today, the Nazca Lines are unsolved mysteries.

Very good. My corrections are in red and my suggestions in blue/grey.

If you want to sound really natural, you could say "... the most possible plausible is that ...