Roman Catholic churches are specifically designed around the presence of the tabernacle, which houses consecrated Eucharistic hosts.
When celebrating the Mass, the early Christians knew that they could not simply dispose of the left-over Eucharistic bread and at first, because they were being persecuted and did not have churches, they distributed all the remaining hosts to be carried to the sick and home-bound.
When the persecution ended, Christians started to build churches and, at the same time, tabernacles to house the reserved Blessed Sacrament.
Place of greatest honor
The Catechism of the Catholic Church explains where tabernacles should be placed inside a Catholic Church:
The tabernacle is to be situated "in churches in a most worthy place with the greatest honor." The dignity, placing, and security of the Eucharistic tabernacle should foster adoration before the Lord really present in the Blessed Sacrament of the altar.
In 2004 the Vatican issued the instruction, Redemptionis Sacramentum, which built upon this idea that was expressed in the Catechism:
According to the structure of each church building and in accordance with legitimate local customs, the Most Holy Sacrament is to be reserved in a tabernacle in a part of the church that is noble, prominent, readily visible, and adorned in a dignified manner” and furthermore “suitable for prayer” by reason of the quietness of the location, the space available in front of the tabernacle, and also the supply of benches or seats and kneelers.
Pope Benedict XVI went further and gave specific instructions on this topic in Sacramentum Caritatis:
It is therefore necessary to take into account the building's architecture: in churches which do not have a Blessed Sacrament chapel, and where the high altar with its tabernacle is still in place, it is appropriate to continue to use this structure for the reservation and adoration of the Eucharist, taking care not to place the celebrant's chair in front of it. In new churches, it is good to position the Blessed Sacrament chapel close to the sanctuary; where this is not possible, it is preferable to locate the tabernacle in the sanctuary, in a sufficiently elevated place, at the centre of the apse area, or in another place where it will be equally conspicuous.
Above all, the tabernacle is put in a prominent place because of what it holds, Jesus Christ himself under the appearance of bread.
