Searching Runes

I soon reached the grey wall, which looked smooth, but when one is touched, they would feel the faint roughness of micros granules on the wall's surface.

Clang Clang Clang

Touching the wall for a few moments, I took out my sword and begin hitting it with all my strength, but I stopped after a few attacks when I found my attacks are not making even a scratch on them.

Shaking my head, I begin to observe the wall, seeing if there is something different on it. 

Hun!

I looked left and right for fifteen minutes and about to give up when I suddenly spotted something. It is a thumbnail size thing, shining in golden light; it looked like a small dot in a giant wall that, simple glance, would not be able to find it.

It is about one hundred and twenty meters above the ground, and I quickly moved toward it, and soon, I appeared in front of it.