Don't be fooled by its simplicity; considering its height and the difficulty of its construction, if this were in the human world, it would definitely be considered a marvel.
Not only is this the headquarters of the Council of the Undead, but it is also the home of the Undead Holy Fire. If translated into human terms, the Undead Holy Fire would be equivalent to the Ministry of Education.
The Undead Holy Fire bears the task of knowledge transfer. By simply coming here and casting one's thoughts into the Holy Fire, one can receive the knowledge and memories engraved within it. The amount one can learn depends on the wisdom and strength of one's soul.
Although Golden Skeletons and Iron Skin Zombies possess intelligence and sufficient soul strength, do not expect them to receive much knowledge.
Witches and the Undead, even those of the lowest level, can absorb a great deal of knowledge. By staying here for a few years, one can become a scholar or mage with profound knowledge.