Discovering The Gate

When they reached the big entrance of a cave At a crater rim, illuminated by the sun They saw the lava tubes, where living is safe Now explorations should be done Suddenly they realized traces of a big driving vehicle on the stony ground It is only to see in the direct light They come from the valley nearby and are leading to the cave they found What a frightening sight Who was here before? - and what shall we find more Following the traces into the lava tube they stopped and could not believe what they saw The way was complete blocked with a mighty round metal gate. What is it made for Who was here before? - and what shall we find more