King's Tomb

In The Adventure of Link, King's Tomb is located in the Graveyard and to the southwest of the Harbor Town of Mido. It can be assumed that this is the burial site of the fallen King of Hyrule who once used the entire Triforce to govern the kingdom of Hyrule. The King's Tomb can be easily spotted as being a lone cross in the middle of the entire Graveyard.

The grave serves as an important landmark in the game, for it is Error of Ruto that informs Link of a secret tunnel to the south of King's Tomb that leads to the Island Palace.

The Legend of Zelda comic
In the Legend of Zelda comic, the Old King's Tomb is one of the many places that Link and Princess Zelda must cross to reach the Island of Hyron. After Zelda reveals to Link that she wishes to reach the Island of Hyron to obtain the Magic Flute that will warp her and the Triforce of Wisdom far away from Ganon's grasp, the young hero comments that they will have to cross through the King's Tomb on their way to the island.

Trivia

 * In the Japanese version of the game, the King's Tomb area features different colors and a darker sky. Instead of the old woman, Link will find a few Bots and a Goriya.