Alcatraz

The Duel Tower was a structure built by Seto Kaiba, that was used to stage the finals and semi-finals of the Battle City tournament.

History
The tower itself is built on a small island. While Gozaburo Kaiba was in change of KaibaCorp, the island was used for KaibaCorp's military base and known as Alcatraz. After Seto came into power, he tore down Alcatraz and constructed the Duel Tower to emphasis the company's shift from military to gaming.

After the Battle City finals, Seto and Mokuba Kaiba had the building self-destruct to get rid of their memories of living with Gozaburo.

Part in the Battle City finals
The inside of the tower was sued to stage a battle royale to determine the match-ups for the semi-finals. Each finalist stood in an elevator like platform in a corner of the room. As their Life Points lowered, they were lifted higher up. The first two to the top, would face each other first semi-final and the remaining two would face each other in the second.

With Seto Kaiba set on facing Yugi Muto, Joey Wheeler set on facing marik Ishtar and Yugi supporting Joey's choice, Marik and Joey's Life Points hit 0 first, pairing them up for the first semi-final and leaving Yugi and Kaiba for the second.

The semi-finals and finals each took place on top of the tower.

Kaiba faced Joey in a third place playoff, just outside the tower.