Vatican City (Agenzia Fides) - The plan for the building of the church is complex and articulated. It is based on the concept of the act of worship which the place is destined to host and manifest. Corresponding to the logic of the Incarnation, through which spiritual realities find expression in sensitive realities, the sacred place is the corporal shell of the liturgical action; it is «symbol and icon» of the Church, the «mystical Body» of Christ. Therefore the plan of a church-building stems from the ecclesial ritual and cultural understanding of the place of worship. The first is due to the Church’s diverse reflection at the theological, ecclesiological, liturgical and spiritual level keeping in mind however the perennial nature of the grounding lines; the second to the diverse psychological, social, cultural structure. Keeping in mind these two fronts correct inculturation of the faith in the ritual act is achieved. This is all important and must be assumed by the planners.
Ecclesiality in planning places of worship - The building of a church is an ecclesial event since it symbolises the Christian community as it celebrates the «divine mysteries» a «foretaste of heaven». The plan for a place of worship demands therefore fidelity to the doctrinal data, as well as spirituality and creativity. These requisites are indispensable. In fact creative genius is capable of inventing architectural forms to express contents reflecting the ecclesial vision. The architect using his personal spiritual openness must grasp the Christian religious sense in order to express it in places which meet liturgical demands.
The paradigm of the Gospel - Consistent with the general principle of religion «in spirit and truth» (Jn 4,23), God can be adored everywhere, specific places are unnecessary, above all He must be adored in the heart, in truth and charity, in the spirit of the  Word incarnate. This explains the scarcity of New Testament references to special architectural models.
The Gospel mentions, as theological «places» of worship in a salvation perspective, the Upper Room, Calvary, the empty Tomb. The Upper Room is a meeting hall described as «magnum et stratum», that is, a suitable place for the guests, properly carpeted, secluded and quiet (cf Mk 14,14-15). Calvary is an infamous place, outside the walls of Jerusalem, used for executions, and therefore in complete contrast with any sacred dedication (cf Heb 13), celebrating the eclipse of the divine in the Kenosis of the incarnate Word. The Tomb instead is a dignified place, hewn in the rock, although destined to contain moral remains, never used. In the Upper Room Jesus institutes the Eucharist as a memorial to make himself present through the centuries; on Calvary he celebrates the sacrifice of his death for the redemption of humanity; in the Tomb he celebrates his descent into hell and his glorious resurrection to fulfil «words and deeds» present in the Scriptures. These «places» theologically understood are combined in the concept of the Christian altar, sign of worship par excellence, in Christ altar of sacrifice, convivial table, reminder of the Tomb. The altar is therefore the architectural fulcrum of the place of worship in which it stands.
The first Christian community abandons the Temple and synagogue and Judaism and opens to the nations. The «place» of evangelisation is the diaspora of the believers «to the ends of the earth » (Acts 1,8), hence all forums can be used to announce «Christ, crucified and risen». The «place» for the «fractio panis» is any ordinary home ranging from the modest lodgings at Emmaus on the shores of the Sea of Galilee, to the Upper Room, to Rome’s patrician houses, «domus ecclesiae». Great respect is given to the «place» of burial, especially for martyrs, and the early Church in Rome uses the catacombs as a privileged place for the dead «awaiting the resurrection on the last day ». Later the numerically grown community will adopt from Roman architecture the «basilica» as its public «place» of worship. + Mauro Piacenza, President of the Pontifical Commission for the Cultural Heritage of the Church, President of the Pontifical Commission Sacred Archaeology. (Agenzia Fides 17/10/2006 - righe 52, parole 630)