Our personal preferences regarding the placement of the Tabernacle are irrelevant. The Church has issued several documents, when taken together, provide a definitive answer about the placement of the Tabernacle in ordinary parish churches.
Several years ago, my parish priest asked me to research the proper placement of the Tabernacle in parish churches (keep in mind that different rules apply to Cathedrals and Basilicas).
I treated the assignment as if I were researching and writing a legal brief. These are my conclusions based on my research:
Code:
1). There can only be one tabernacle in a church (Code of Canon Law, section 938, subsection 1).
2) The tabernacle must be located in the church, not in a separate chapel located outside the main church building (Eucharisticum Mysterium, sections 53-54; Inaestimabile Donum, section 24; Code of Canon Law, section 938, subsection 2; Catechism of the Catholic Church, sections 1183, 1379).
3) The tabernacle must be located in a prominent (e.g. readily noticeable) place in the church (Inter Oecumenici, section 95; Inaestimabile Donum, section 24; Code of Canon Law, section 938, subsection 2).
4) The tabernacle must be located in a truly noble position in the church (Inaestimabile Donum, section 24).
5) The tabernacle must be located in a conspicuous (i.e. obvious) position in the church (Code of Canon Law, section 938, subsection 2).
6) The tabernacle must be located in a part of the church that has been beautifully decorated (Code of Canon Law, section 938, subsection 2).
7) The tabernacle in which the Eucharist is regularly reserved must be immovable (Code of Canon Law, section 938, subsection 3).
8) The tabernacle must be located in a most worthy place with the greatest honor (Catechism of the Catholic Church, sections 1183, 1379).
While the tabernacle does not have to be located on main altar there is nothing in the documents of the Second Vatican Council or the post-conciliar documents that prohibit it. On the contrary, several documents specifically mention the main altar as an appropriate site for the tabernacle. It is difficult to imagine a place for the tabernacle that could have more prominence, is more conspicuous, has greater honor, or has more nobility than the main altar.
“Built of Living Stones” was published by the National Conference of Catholic Bishops (now known as the United States Conference of Catholic Bishops). This document states that it is a replacement for Environment and Art in Catholic Worship (EACW). However, “Built of Living Stones” is not an official document and therefore is not legally binding on Catholics, despite having been published by the American Catholic Bishops
Code of Canon Law, section 455, lays out the requirements for a conference of bishops to issue general decrees. It requires a two-thirds vote by all the members of the conference. It also states that “…such degrees do not have binding force, unless they have been legitimately promulgated, after having been reviewed by the Apostolic See.”
“Built of Living Stones” was not submitted for a two-thirds vote of all the American Catholic Bishops. Instead, it was submitted for a majority vote of the bishops in attendance at their November 2000 meeting. The document was approved by a voice vote, without a counting of the yeas and nays. To the best of my knowledge, it has never been submitted to the Holy See for approval.
The Preface of Built of Living Stones describes the document as a set of "guidelines that can serve as the basis for the diocesan bishops to issue further guidelines and directives for their dioceses. The Preface goes on to state:
“Where the document quotes or reiterates norms from liturgical books and the Code of Canon Law, those prescriptions are binding on local communities and dioceses."
Therefore, by its own wording, Built of Living Stones is only binding on American Catholics when it quotes from official, authoritative sources such as Canon Law or liturgical books approved by the Magisterium.