Las Noches, is the fortress located in Hueco Mundo and base of operations of the Espada. They reside there with their army of Arrancar complete with medical facilites and detention wings. Las Noches is a massive fortress which can be seen for miles in Hueco Mundo. It consists of a main building with a domed center surrounded by several large towers and smaller buildings. Atop the dome are six smaller towers, which seem to contain areas such as a throne room and the Espada meeting hall. Like everything else in Hueco Mundo, the main building is colored white. The inside of Las Noches' dome simulate the living world and Soul Society's blue sky. Due to their immense power, the top four Espada are forbidden from releasing their ZanpakutÅ within Las Noches.
The Forest of Menos, is an area below the surface of Hueco Mundo's desert where the average Hollow hide from the Arrancar. Gillian- and Adjuchas-class Menos dwell here, along with possibly Vasto Lorde-class Menos. The forest is filled with large trees made of a silvery quartz substance. These trees extend to the surface and dot the landscape of the desert in Hueco Mundo. The Espada and Arrancar have a considerable amount of influence here, judging by a large group of Hollows bowing down upon the Espadas Rule.