Inheritor

The fifth layer was more like a mansion with many rooms, an indoor garden, an empty library, a dining hall, and other facilities like training rooms and others. The more that they walked through the fortress, the more Arthur realized that someone must have lived here for a while. 

When you compared each layer to the last, you would realize that more work was done to it in comparison. In the fifth layer, the gears were no longer seen and what remained was tiled floors and varnished wood. However, it seems that the place wasn't probably taken care of, as dust filled the halls and corridors. 

"Just how big is this place?" Ivy muttered in fascination as the two made their way through another set of rooms and a hall. 

"Space expansion runes are used excessively, so you can't judge from its outside appearance," Arthur answered as his thoughts drifted elsewhere.