<P> In the liturgy of the Roman Rite of the Catholic Church, the altar is the structure that holds the Tabernacle, and in the Extraordinary form Mass on which the Sacrifice of the Mass is offered . In the Novus Ordo, the tabernacle is now often moved off to the side . Mass may sometimes be celebrated outside a sacred place, but traditionally never without an altar, or at least an altar stone until recent changes, a corporal now being sufficient . </P> <P> In the rites used in the Eastern Catholic churches, altar can also refer to the whole space surrounding the table within the church building (the area called the sanctuary in the West), with the table itself called the Holy Table . </P> <P> In ecclesiastical history we find only two exceptions: St. Lucian (312) is said to have celebrated Mass on his breast whilst in prison, and Theodore, Bishop of Tyre on the hands of his deacons . According to Radulphus of Oxford (Prop. 25), Pope Sixtus II (257 - 259) was the first to prescribe that Mass should be celebrated on an altar, and the rubric of the missal (XX) is merely a new promulgation of the law . It signifies, according to Amalarius the Table of the Lord (mensa Domini), referring to the Last Supper, or the Cross, or Christ . The last meaning explains the honour paid to it by incensing it, and the five crosses engraved on it signify his five wounds . </P> <P> In the earliest church buildings, the altar was situated in a way that the priest faced east during the prayers of the Eucharistic liturgy . Depending on the particulars of the specific church building in terms of space and orientation, this usually meant that the altar was placed at the east end, although there are also some notable exceptions, such as the Constantinian St. Peter's Basilica and the Basilica of Saint Paul Outside the Walls, wherein the altar was at the western end . This meant that in order for the celebrant to face true east during the Eucharistic prayers, he needed to stand on the western side of the freestanding altar and face towards the doors of the church . These are not, however, examples of ancient churches in which the priest or bishop celebrated the eucharist "towards the people," as congregations in these churches would stand in the side aisles, facing the altar during the scripture readings and homily but facing east along with the celebrant during the eucharistic prayer . </P>

Where is the altar located in a catholic church