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an early Christian or medieval church of the type built esp. in Italy, characterized by a plan including a nave, two or four side aisles, a semicircular apse, a narthex, and often other features, as a short transept, a number of small semicircular apses terminating the aisles, or an atrium. The interior is characterized by strong horizontality, with little or no attempt at rhythmic accents. All spaces are usually covered with timber roofs or ceilings except for the apse or apses, which are vaulted.