This room, located beside the north entrance, resembles a cistern. Its floor is lower than the surrounding area and is reached by steps. The "Lustral Basin" was surrounded by columns and was lined with slabs of gypsum giving it a luxurious appearance. In its present form, the area has been completely reconstructed by Evans.
Areas with a similar arrangement have been found in other parts of the palace of Knossos, as well as other palaces and important Minoan buildings of the period (1700-1450 B.C.). It is not known how these places were used. However, from their construction it seems that theu would not have been filled with water, nor was there any drainage. Evans thought that they were used in purification ceremonies and therefore called these places "Lustral Basins". Evans also believed that the Palace was a sacred place. That is why, in his opinion, the "Lustral Basin"in question was used to purify visitors going into th Palace via neighbouring North Entrance.