Introduction to the Tomb of the Unknown Soldier: The four walls of the tomb of the Tomb of the Unknown Soldier are made of reinforced concrete and cast with soil. In the middle is a circular black polished granite tomb with a diameter of seven meters. In the tomb is a white marble sarcophagus. Behind the pool is the altar. There is a perpetual flame burning on the altar, symbolizing that the flame of life of the martyrs will never go out.