A hall projecting in front of the façade of a church, found from the fifth century both in the East and the West. In western Europe it was generally a narrow open ante-chamber with sloping roof and closed on the smaller sides, which were probably, when connected with the main buildings, provided with apses, as in the baptistery of San Giovanni at Rome. In the East, especially in Syria, this ante-chamber was given a fine façade, and was flanked by two towers. It was also frequently closed in front in Oriental countries and entered by one or three doors, and often had two stories, as in the churches of Turmanin and Suweda. The purpose of the vestibule, at least in western Europe, was not to provide a resting-place for penitents, but to deaden the noise outside. In medieval times Italy held firmly to the simple open chamber with sloping roof. North of the Alps, however, the vestibule developed into a projecting structure united with the main building, recalling the Syrian churches. The method of construction shown in the palace church of Charlemagne at Aachen, an ante-structure of several stories between the two western round towers, was adopted in the early Romanesque period, especially by the Cluniac monks. The Romanesque architecture also made use of a covered ante-structure placed before the west front. This style was first used on a large scale in the cathedral at Speyer, where the vestibule has three stories. The churches in which the main entrance was on the side aisle had a vestibule or portico (called the "Paradise") on the same aisle, as in the cathedrals at Münster and Paderborn. The name "Paradise", originally given to the atrium, was given later to the ante-chamber. In Gothic architecture the vestibule was reduced in size, and became an ornamental baldachino-like structure, which also served as an entrance, as in the cathedral at Freiburg in Baden. The name "Paradise" for the vestibule explains the festival, popular among the common people and called the Expulsion of Adam, held at Halberstadt as early as 1391, and which took place in the vestibule. In the Middle Ages alms were distributed and offerings made in the vestibule. The latter was used at times also for judicial proceedings, and in many such ante-chambers the announcements of the standard weights and measures were posted up, as at Freiburg in Baden the standard weight of bread in 1270, 1317, and 1320.
In Italy the architecture of the Renaissance and of the Rococo style held to the vestibule, which had been made sacred by tradition. Alberti considered its use necessary on all occasions. Even basilicas, as San Giovanni in Lateran and Santa Maria Maggiore, received new porticoes, which in the two churches mentioned were constructed as loggias in two stories. These vestibules were detrimental to both churches, concealing the façades and giving the buildings a somewhat secular appearance. The Carmelite church at Arezzo has a vestibule with columns built by Benedetto da Majano.