Slytherin

Gryffindors, Hufflepuffs, and Ravenclaws stray away from the lower dungeons of the castles, finding it eerie and out right spooky. However, the Slytherins feel right at home. When given a password to it's entrance somewhere in the dungeons, Slytherin's retreat to their House built under the Lake. With cool damp air, the entire House is enriched with a greenish glow, much to the fancy of it's superior inhabitants.