The Dark Tower is never seen in the book
The Dark Tower is a location featured in The Crystal Trap. Situated in the main street of the Town of Ruto, it is the resting place of Ganon's Handprint, which is one of the three items necessary to free Link from the Crystal as dictated by the Fairy's Scroll.
When Princess Zelda enters the Dark Tower, she will be greeted by a Darknut, who promptly attacks her upon sight. By shooting an arrow at the Darknut's back, she defeats the foe and climbs up the tower.
After a long climbing of stairs, Zelda comes out at the very top of the spire to find herself above Ruto Town. The princess begins to think that the Darknut was there for a reason, and that it must have been guarding something important. Just then, she sees a Handprint pressed into the stone near the battlement. Realizing that it is Ganon's mark, she thinks of the Fairy's Scroll riddle and figures out that Ganon's touch is the coldest thing in the world. Using her dagger, Zelda makes the handprint come free from the floor and heads out of the tower and into the Tavern.
- "She goes out to the main street of Ruto and looks around. Looming over everything is a dark, evil-looking tower with five curved stone spikes on its top." (The Crystal Trap (Archway), pg. 24)
- "'Welcome!' an inhuman voice whispers from the shadows. 'Who's there?' Zelda demands, pulling back on her bowstring. A tall, armored figure steps into the moonlight. 'A darknut!' Zelda whispers. Without another word, the evil knight charges, his shield held high, his long blade slicing the air." (The Crystal Trap (Archway), pg. 49)
- "Zelda trudged up the stone staircase. After a long climb, she comes out at the very top of the spire. All Ruto is beneath her. 'That darknut was here for a reason,' she says. 'It was guarding something. What?'" (The Crystal Trap (Archway), pg. 49)
- "Her eyes travel over the battlement and stop on a strange object set in the floor. [...] 'A handprint!' she says in surprise. 'Pressed into the stone. And that mark!' [...] 'That's Ganon's mark! It must be his handprint.' Then she thinks of the riddle. 'What's colder than ice?' she says. 'Ganon's hand! His touch is the coldest thing in the world.'" (The Crystal Trap (Archway), pg. 44)
- "With the point of her dagger, Zelda carefully priest at the stones around it until the handprint comes free. She slips the print into her pouch." (The Crystal Trap (Archway), pg. 44)