A butterfly roof (sometimes called a V roof) is a form of roof characterised by an inversion of a standard roof form, with two roof surfaces sloping down from opposing edges to a valley near the middle of the roof. It is so called because its shape resembles a butterfly's wings. Butterfly roofs are commonly associated in the US with 20th century Mid-century modern architecture. They were also commonly used in Georgian and Victorian terraced house architecture of British cities, where they are alternatively termed "London" roofs. The form has no gutter as rainwater can run off the roof in no more than two locations, at either end of the valley, often into a scupper or downspout. The form may be symmetrical, with the valley located in the center, or asymmetrical with an off-center valley. Th