
Incidentally, I'm not aware of any Arnorian lords being buried there. The last Prince of Cardolan was supposed to be buried in the barrow that the Ringbearer was later trapped in, but he was not a lord of Arnor, if you know what I mean (also he died in the downs, and might only have been buried there out of convenience).
Certainly the body could have been brought back north at this time, though also it could have been left in the houses of the dead in Minas Tirith.
But when this was done, and Eorl had returned to the North to bring back all his people to their new dwelling, Cirion removed the tomb of Elendil. ...The casket therefore that Isildur had set within the mound Cirion removed to the hallows of Minas Tirith ...
Sheesh, I hope Denethor didn't burn up the casket in his madness!