**QUADRIPORTICO** – Q. of the basilica of St Paul – Rome.
The attribution to QUADRATUS (v.) is uncertain. The notice in Philip of Side seems to be a combination based on Eusebius with a false attribution to Papias. The recent attempt by Andriessen to attribute to Q. the Epistle to Diognetus (v.) remains in the realm of hypothesis. The notices of St Jerome (De vir. ill., 19; Ep. 70 ad Magnum, 4: PL 22, 667) are nothing more than combinations.
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QUADRIPORTICO.
Varro, in *De Lingua Latina* (V, 161), defines the peculiar function of the atrium or quadriportico as a space “qui esset ad communem omnium usum.” This essentially remained its purpose, which explains its adoption in the architectural complex of the Christian basilica.
The quadriportico of the great basilicas was enclosed on all four sides by colonnaded porticoes; it could adjoin the façade directly or communicate with the narthex (v.), the interior space from the exterior, and served, in the absence of the latter, to accommodate penitents and catechumens. At its center stood a large basin (cantharus) for the faithful’s purificatory ablutions before entering the temple; as Eusebius attests (Hist. eccl., X, 4, 1) for the basilica of Tyre, the font was considered indispensable, and as in ancient St Peter’s in the Vatican, it was sometimes covered by a canopy supported by four columns or protected by enclosures. This primitive nature of the quadriportico soon declined into the more humble function of a pilgrim’s shelter and burial place; in parallel, the more noble appellation of *paradisus* came into use. Later, in Rome and elsewhere (S. Clemente, S. Maria in Cosmedin, S. Prassede; Cimitile near Nola, etc.), in place of the usual arch or vaulted entrance communicating with the street, aediculae supported by columns appear, the so-called *protiro*. In the East, sacred architecture preferred only the narthex.
With the spread of monasticism, new spaces were added to the rear of the church, and to isolate the community, the center of the cenobium with its well or fountain—reminiscent of the quadriportico’s font—was preferred (v. Chiotoro). The atrium, however, did not disappear entirely: from S. Ambrogio in Milan (11th century) to S. Maria de’ Pazzi in Florence (15th century); from S. Gregorio al Celio in Rome (17th century) to the Ostian basilica of St Paul, reborn from the fire; the quadriportico survived in artistic taste, perhaps because its welcoming silence and dim light invite the soul to recollection and prayer.
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