Some of them are more than 32km long. A theory has been put forward that the Nazcan people could fly. Evidence shows that they had the technology to put together a hot-air balloon. So the Nazcans may have been able to organise the drawing up of the lines and figures from the air. But the theory has yet to be proved.
Some people think the lines are landing directions for spacecraft.
Others believe they are maps of the stars, used by the Nazcan people to tell them when to plant and harvest their crops. Between 1980 and 1991 strange shapes suddenly began appearing in farmers' fields in the south of England. Huge, perfectly shaped circles were etched into cornfields overnight - at first no one knew how they were made or who created them. Crop circles are now known to be elaborate hoaxes, but there are still those who dismiss the logical explanation and believe that the circles were made by aliens trying to get in touch with us. Horse box The White Horse at Uffington in Oxfordshire measures 114 metres across and, like other carvings, can be seen from many miles around.