Minecraft wiki entry for Curved_roofs, associated text: A roman arch is simply a semicircle. An arched roof that uses a roman arch is simply a barrel roof. A gothic arch is pointier. You can generate a gothic arch by drawing two circles of the same radius so that they overlap. To make a pointier arch, move the centers of the two circles further apart. Gothic roofs are rare on residential buildings, and are much more likely to be found on larger buildings such as meeting halls, churches and other such structures. Even barns may have gothic roofs, although they tend to have quite 'fat' arches rather than the much sharper curves seen for churches. There are many technical terms for other types of arches, but they are usually used for openings inside a building, not as its main roof shape.