The Black Column

You have died! You wake up in the middle of a desert with no memories of your past life And nothing but the clothes on your back and a single knife. In the far distance you can see a single black column stretching far into the sky beyond the clouds. As You get closer to the black column, You come to a cliff and then you see it for the first time. It is a labyrinth so massive that you could fit Three large cities into it. You descend the cliff and reach the walls of the labyrinth. At the base of the labyrinth is a single keyhole.