Atrium
Introduction
Atrium (from the Latin atrium) is the closed and usually porticoed area that precedes the entrance of a building. In Roman architecture, it was the patio of the domus (rich Roman house) and of some Roman temples, then it passed to the early Christian architecture and from this to the medieval one.
In churches "Church (building)") is a porticoed patio located at its foot and which serves as access. It used to have a fountain "Fountain (architecture)") and arcades. Access was free to anyone to the atrium, leaving the interior of the temple reserved for the faithful.
In ancient temples there were several types of delimitation of the sacred precincts external to the temple building itself, but around it (peribolos, temenos, templum, sacellum). In fact, in extreme cases, the temple could be reduced to a mere altar without any cover, but there was always a delimited area that was considered sacred and should not be profaned (dedicated to other uses).
Many churches have an atrium at their entrance, although its form and functions are very different from those of Roman times. It was very frequently used as a cemetery. In general, it is usually marked with columns "Column (architecture)") and sometimes with chains "Chain (object)"), marking the limits of the sacred precinct (sagrera in Catalonia). In the Old Regime it had a function of jurisdictional demarcation of the ecclesiastical jurisdiction, and even those persecuted by ordinary justice were allowed to "take refuge in the sacred" (asylum in sacred). The universities, born as ecclesiastical institutions, also had such facilities.
Atrium, portico, arcaded gallery, portal, arcade and other related terms
The DRAE differentiates "portico" and "atrium", identifying this with the space limited by a plurality of that: Atrium: open space, and usually surrounded by porticos, which is found in some buildings. The same dictionary indicates that it is usual for the atriums to be paved and at a higher level than the street, and considers the term vestibule synonymous.[1] It also identifies it with "vestibule": Atrium or portal that is at the entrance of a building. In large hotels, a large room near the entrance of the building. Covered space inside the house, which connects the entrance with the rooms or with a patio. Reception, room that gives entrance to each of the rooms inhabited by a family.[2].