Monument of Ruin

Monument of Ruin aka Fake Nazarick is a structure located in the center of the Great Forest of Tob.

Background
Ainz Ooal Gown wary of the New World and its potential dangers, commissioned its creation. Aura Bella Fiora was the major architect of the structure, it was to provide a hiding place in case there was an emergency and he could not return to the Great Tomb of Nazarick. In addition, it would act as an alternate base of operations to avoid Nazarick’s location being revealed.

The Dark Hero Arc
Ainz commissioned Aura to create a eddifce that would serve as a shelter in case any denizen from Nazarick was attacked by an unknown force.

The Show Must Go On!
Aura started work in creating the secondary base with the help of several Dragonkins. Mare had tagged along and was confused at the purpose of the structure. And when Aura declared that she was building a second Great Tomb of Nazarick, Mare became concerned as he feared it meant that she was seceding from Nazarick. However Ainz arrived and explained that the base would serve as a base to lure potential enemies in case anyone from Nazarick was attacked.

The Sealed Evil Tree Arc
Aura reported to Ainz that everything was going smoothly with the constructions when she met with him and Hamsuke. Later after meeting the dryad, Pinison Pol Perlia and learning of the existence of Zy'tl Q'ae, Ainz wished to observe it, worried it might be a threat to his new base in the forest.

The Lizard Man Heroes Arc
Aura is seen directing several elder liches, golems and imps. When her watch declares it to be be lunch she orders them to take a break. Aura managed to finisih building the structure, in time for Cocytus to use it as a base of operations to direct his undead army at the Lizardmen Alliance.

Later after Cocytus failed in his mission, Ainz and the Floor Guardians used it to safely watch the fight between the warriors of the Lizardmen and Cocytus.

The Two Leaders Arc
The construction of the structure was noticed by several native inhabitants of the Tob Forest. Those that approached the structure, were killed. The Gigu Tribe for instance learned of its existence when several of their surviving warriors brought news of it to them. From them they learned that a new power was now spreading in the forest, one that commanded powerful undead and monsters. The two remaining members of the Three Monsters also too notice began to amass an army together to drive the new power out. The Gigu Tribe opted to escape the forest, splitting up before war broke out, but in their weakened stated fell prey to adventurers and the rest captured by the Giant of the East. Word of the rising power was brought to Carne Village by a hobgoblin named Agu.

Trivia

 * It was originally unnamed, but the inhabitants of the New World had given it one.
 * The Monument of Ruin was also used to store all manner of supplies and resources.