The Nazca Lines are one of those wonders, where no-one actually knows how, when and why they are here. As usual there are plenty of theories, including some that even involve extraterrestrials…
The most likely scenario though seems to be, that the lines have been created by several people over centuries and millennia – with the earliest culture dating back to as far as 900 b.c. and the youngest to around 600 a.d.
The question about their purpose also returns an array of possibilities – from being an astronomical calendar, running tracks – to signs for extraterrestrials… Just have a look yourself.