Apse of the sacellum

It is a vertical architectural structure with a semicircular shape, covered by a brickwork vault, called a dome or semi-dome; in some cases the roof is made of wood with supporting beams placed like the rays of the sun.
In the case of an aedicula, semi-open and/or delimited by walls, the apse is used to underline the importance of the room, intended for a particular function.