Order the church as a single path: a colonnaded atrium, a narthex, the long nave drawn toward the altar, and the apse framed by a triumphal arch at the end of the axis.
Enclosure, gateway, forecourt, fountain
Wall the whole precinct; open a great gateway toward the approach; before the church set a court open to the sky with porticoes on four sides and fountains in it, where those who enter may wash before they go in by the three doors.
Eusebius preached at the dedication of the new cathedral of Tyre in about 315 and described it as a sequence of thresholds: the outer wall that makes the precinct a sacred place; the lofty gateway, turned to the rising sun, which draws in even passers-by; the colonnaded forecourt, where those not yet baptised could wait; the fountains for cleansing; the three doors, the middle one grandest; and within, the thrones, the benches and the altar fenced by a lattice.
At Tyre the entrance was on the east. In most later churches the forecourt lay to the west, before the façade, as at Old St Peter’s and at the Lateran, and the eastward apse of the Apostolic Constitutions turned the whole sequence round; but the sequence itself (precinct, gate, atrium, fountain, narthex, nave) became the standard approach to the great churches of the fourth to sixth centuries.
Related rules
Make a basilica between a third and a half as broad as it is long; make each aisle a third of the width of the central space, and the columns as high as the aisles are broad.
W = ⅓ to ½ L; aisle = ⅓ nave; column height = aisle width; upper columns ¼ smaller
Lay out the church as an Early Christian basilica (a tall nave lit from above, lower aisles on either side, a sanctuary ending in an apse to the east) and cross it with a transept, so that the plan becomes a Latin cross with a tower over the crossing.
Build the house of assembly long, with its head toward the east and rooms for the clergy on either side of the east end; seat the bishop in the middle of the head with his presbyters about him, and the people in order down its length.
Build the baptistery, and its font, with eight sides, because the eighth day, the day of the resurrection, is the day into which the baptised are born.
plan and font = octagon (8 = 7 + 1, the day after the Sabbath)
Bury no one inside the city; keep bodies, urns and sarcophagi outside the walls, even the relics of apostles and martyrs. So the great shrines of the martyrs rise in the cemeteries along the roads, not in the town.
Cite this page Chris Paton, “Enclosure, gateway, forecourt, fountain”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/eusebius-atrium. Text, drawings and models licensed under CC BY-NC 4.0.