The Wall of Heroes was a memorial on Andoria.
Shran explained to Naarg, that when Guardsmen die far from home, their companions carry part of him or her back to the ice of Andoria. (ENT: "United")
Shran promised to take Archer's blood to the Wall of Heroes if he lost their Ushaan duel, but Archer declined, saying that he wasn't going to die that day. (ENT: "United")