The Tower of Druaga: The Aegis of Uruk (ドルアーガの塔 〜the Aegis of URUK〜) and its sequel, The Tower of Druaga: The Sword of Uruk (ドルアーの塔 ～the Sword of URUK～) , is an anime TV series, created by Gonzo, and is an animated continuation of Namco's Babylonian Castle Saga video game franchise which began as an arcade game, The Tower of Druaga, originally released in 1984.

Story:
It has been eighty years since King Gilgamesh defeated "the tower" single-handedly, and now the tower is reborn again. The "Summer of Anu" is a season that comes every few years during which the powers of the monsters within the Tower wane thanks to the grace of the great god Anu. Each Summer of Anu, the armies of the Uruk Kingdom secure their strongholds within the Tower, aiming to eventually conquer the upper floors. The story begins with the third Summer of Anu. The city of Meskia is the first stronghold built on the first level of the Tower. In addition to the Uruk Army preparing for their third campaign against Druaga, innumerable adventurers called "climbers" have been drawn to Meskia by rumors of a legendary treasure believed to be hidden on the top floor of the Tower.
Jil, a young guardian, has traveled to the tower and Meskia, the last safe stop on the first floor of the tower. Jil wants to gain the Blue Crystal Rod, the legendary treasure that resides on the top floor of the tower. On the top floor is the evil lord Druaga, and numerous monsters along the way.

The second season , titled The Tower of Druaga: The Sword of Uruk , picks up "half a year after" the events of the first season. With Druaga's guardian defeated, the monsters of the tower have disappeared and a period of peace and prosperity have descended upon the people. Jil and Fatina, having survived the tower's collapse, attempt to move on with their lives while still coming to terms with Neeba and Kaaya's betrayal. This all changes when they rescue a mysterious girl from a group of soldiers. They learn that this young girl, Ki, may be the key to unlocking a great secret within the tower. Armed with this knowledge and haunted by a troubling vision of the future, Jil once again prepares to climb the tower.

Source:Wikipedia