“Tam Co” cave (the Eight Lady Cave) is located at km16+500 on the Road No.20 which is part of the legendary Truong Son trail, the cave also bore witness to the sacrifices of the force of volunteer youth during the fight against the American, especially the eight volunteers of the age of 20 years (a native of Hoang Hoa district, Thanh Hoa province) whose sacrifices became the symbolic of patriotism.

During the American War, the area was a target of fierce aerial bombardments of the American to stop the northern reinforcement to the southern front-line and marked the terrible bloodshed of the volunteer youth during their attempt to keep the transport route clear. On November 14, 1972, violent bomb attacks were frenziedly dropped down to the land, a huge stone of 1000 tons collapsed to lock 8 voluntary youths inside the cave. Nine days after that, there was no hope for saving their comrades, all 8 voluntary youths sacrificed.
Today, “Tam Co” cave (Eight Lady cave) has become a spiritual tourism destination for travelers.