Castile soap is a plant-based soap made from vegetable oils (olive, coconut, palm) and plant oils. This ancient soap been around since the 11th century and was first made in the Aleppo of the Levant region (modern day Syria). Castile soap can be used to clean just about anything and everything: your face, your laundry, and even a stinky dog! Castile soap comes in both liquid and bar form. Start with 7 money-saving recipes using castile soap.