The atrium was in Roman architecture, a central room in a house (often residential building ); it was widespread in the Roman Empire.
The Atrium is a rectangular space in the middle of the house, the surrounding rooms are accessible from the off. It served as a residence for the family. Light received the atrium through an opening in the roof. The boundaries between the atrium and courtyard are fluid.
The term comes from the Latin ater possibly the atrium, which means as much as blackened. This could be deduced from the fact that originally was also composed of an open fire stove in this room, the smoke withdrew through the roof opening.
In Christian basilicas Atrium, together with the term peristyle the atrium.
Case of Spanish buildings of the Renaissance was formed from the patio. Nowadays the term atrium is also used for a covered courtyard with a glass roof.
Vitruvius mentions a total of five models, where you can share these in atria with and without roof opening. As atrium without opening, probably the older design is the atrium testudinatum - probably from the Latin word for tortoise testudo - to lead. In the other four forms are atriums with opening; they differ in the nature of the construction.
When Vitruvius ( 6, 3, 1) as the atrium tuscanicum ( Etruscan atrium ) rely less design designated the roof of two massive wooden beams supported on which cross two beams are embedded. It developed an upwardly partially open interior, the roof was supported by columns or piers. The atrium with only four columns is tetrastylicum atrium ( viersäuliges atrium ), the atrium with a supported by many pillars opening atrium corinthicum ( Corinthian atrium ) called.
The most common was probably in spite of the expensive beam construction the atrium tuscanicum because it afforded a free Bilck from the entrance into the tablinum or later into the peristyle.
The roof was formed with inclined inward sloping roof usually in the form of an atrium impluviatum. Under the resulting rectangular roof opening, the compluvium was a likewise rectangular water basin, which Impluvium, which was used to catch the forwarded into a cistern rain water. When the atrium was not used simultaneously to collect rainwater, the roof could also be inclined outwards. In this case it is referred to as sodium displuviatum. According to Vitruvius This had the disadvantage that the vertical gutters (Latin fistula ) could not absorb the water so quickly the horizontal gutters (Latin canalis ) and so the water ran down the walls that have been damaged by this.
There were also smaller houses completely covered atriums without a compluvium. This was called atrium testudinatum.