Pasto's Carnival, held in the first week of January, is the most important folk festival in southern Colombia and one of the few in the Americas inscribed on UNESCO's Intangible Heritage list (2009). The pre-Carnival days from 28 December are the Castañeda Family parade and the indigenous Cuyabro parade, but the real event is 4–6 January.
Wear nothing you care about. You will be covered in black grease one day and rainbow powders the next. Hotels book out months in advance.