Lost Mysteries: The Runway

In season 3 of Lost, Kate, Sawyer and Jack have been capture by the Others and are brought to a second island, home to the Hydra Station. Sawyer, Kate and a few other people are forced to do hard labor by breaking and moving rocks. Sawyer later asks Juliette what they were building and she replies a runway ... for the aliens.

So are they really building a runway? If so, why? With the island's properties, we've seen that flying near it causes the aircraft to do some crazy things. Maybe that's why the "runway" was being built on the second island and not the main one. I have my doubts that it was a runway though. What else could the work have been for?

Besides the beginning of season 3 ("The Glass Ballerina" and "I Do"), we haven't seen the runway area again. Sawyer asks Juliette about it in the finale "Through the Looking Glass" but the way she answers about aliens, the audience has doubts about what they were building.

So now that Ben has left the island, will there be more to the runway story? We'll just have to wait and see.