VATICAN - Planning and building God’s house. Contribution by Bishop Mauro Piacenza, President of the Pontifical Commission for the Cultural Heritage of the Church. “The Altar”

Vatican City (Fides Service) - “The altar on which the sacrifice of the cross is made present in sacramental signs is also the Lord’s table at which the people of God are called to participate when they are gathered Mass; the altar is at the centre of the Eucharistic sacrifice of thanksgiving” (OGMR, n. 296).
These fundamental and significant facts which refer respectively to the Last Supper and the Cross on Calvary from the very beginning of the Church inspired the shape of the Christian altar: supported by pillars in a row or in one block as a sacrificial altar. After considerable transformation in intermediate centuries the liturgical reform of Vatican II substantially returned to this typology.
Apart from the typology of cubic altar surmounted by a ciborium characteristic of early Christian basilicas and preserved in various churches especially in Rome, liturgical requirements in the Middle Ages gradually produced an altar placed further and further back in the sanctuary (or against the walls of side chapels), rectangular in shape and accessible only from the front because at the back it had either a “capsa” containing the relics of a saint or a painted or sculptured ‘backdrop’. The Council of Trent determined the definitive shape of the ‘wall altar’ surmounted by a painted icon, or detached from the wall and decorated with statues with the tabernacle set at the centre.
Placed upon a sanctuary distinct from the hall by means elevation to indicate the distinction between ordained ministers for which this part is reserved but not separated from the rest of the building, the altar must be clearly visible from every part of the church since it is there that the memorial of the death and resurrection of Christ is made present while waiting for His return in glory. The altar’s position must allow the ministers to move easily around to incense it and to celebrate Mass facing the people. It is also the principle for the arrangement of other pieces of furniture: lecturn, celebrant’s chair, tabernacle if it is placed in the sanctuary.
A new church must have one, fixed, central altar as a symbol of Christ the “corner stone” of the Church (cfr 1 Pt 2, 4; Eph 2, 20). This is why altars are usually square with no front or back.
The altar will be the place for the Book of the Gospels until the end of the Liturgy of the Word and during the Eucharistic Liturgy for the sacred vessels, the corporal and the Missal; flowers and candles may therefore be placed next to the altar which on no account must not serve as a support for objects not related to the celebration of Mass. Consequently the size of the altar must be in proportion to its function always in a such a way as not to detract from its importance.
To safeguard its symbolism at least the table of altar should be of marble or some other natural stone and the rest of the construction should be well built in solid, worthy material. The four sides of the altar may be sculptured or painted with themes correspondent to the meaning of the altar, inspired for example by the ample repertoire of Scripture and Eucological readings contained in the Rite for the Dedication of a Church and Altar. As a sign of respect and veneration the altar is covered with cloths of pure linen and other fabrics which can be richly embroidered.
Close to the altar there shall be the crucifix “to call to mind the Lord’s saving passion” (OGMR n. 308); however the Paschal Mystery may be evoked also with other theophanic images, selected from among those used in the great tradition of liturgical art (glorious cross, ascension, Christ Pantocrator etc.).
The altar shall be dedicated with a special Rite found in the Roman Pontifical and on that occasion, according to an ancient custom, it is highly recommended that relics of a martyr or some other saint be placed under the altar to indicate continuity between the sacrifice of Christ and that offered by the Church gathered in the celebration of Mass.  Mauro Piacenza, President Pontifical Commission for the Cultural Heritage of the Church, President of the Pontifical Commission for Sacred Archaeology. (Agenzia Fides 28/3/2006, righe 54, parole 658)