Still unknown why they are made, the Nasca lines form an interesting phenomenon. There are several agencies in town that will fly above the lines for an excellent view. Take some travel sickness medicine before you go because the plane will make lots of turns so everybody can see well...
From the air the figures look pretty small, but if you want to see how big they are you can go to the lookout tower on the highway just outside the town. From there you can see the "hands" and "tree" figures that are right next to the highway and from this close you can see how big the lines really are.