QUADRIPORTICO. - Varro in "De Lingua latina" (V, 161) specifies the peculiar function of the atrium or q. as an environment "qui esset ad communem omnium usum." Such in substance it always remained, and this explains its adoption in the architectural complex of the Christian basilica.
The q. of the great basilicas was enclosed on four sides by colonnaded porticoes; it could abut directly on the facade, or communicate with the narthex (v.), internal or external, and served, in the absence of the latter, to receive penitents and catechumens. At the center, a large basin (cantharus), for the purifying ablutions of the faithful before entering the temple; as Eusebius attests for us (Hist. eccl., X, 4, 1) for the basilica of Tyre, the font was considered indispensable and, as in the ancient St. Peter's in the Vatican, was sometimes covered by a roof supported by four columns or protected by enclosures. This primitive nature of the q. soon declined into the humbler one of a shelter for pilgrims and a burial place: alongside this came the more noble appellation of paradisus. Later, in Rome and elsewhere (St. Clement's, St. Mary in Cosmedin, St. Praxedes; Cimitile near Nola, etc.), in place of the usual arch or the vaulted entrance by which it communicated with the street, there is a small aedicule supported by columns, the so-called protio. In the East, sacred architecture preferred only the narthex. With the spread of monasticism, new spaces were built against the rear of the church, and to isolate the community, the center of the cenobium with the well or fountain was preferred, which recalled the fountain of the q. (v. CHIOSTRO). The atrium nevertheless did not disappear entirely: from St. Ambrose's in Milan (11th century) to St. Mary de' Pazzi in Florence (15th century); from St. Gregory on the Caelian in Rome (17th century) to the Ostian basilica of St. Paul reborn from the fire; the q. has survived in the taste of art, perhaps because its welcoming silence and its half-shadows invite the soul to recollection and prayer.
Bibliography6 works
Pasquale Testini