In times of persecution, the early Christians celebrated the Eucharist over the tombs of martyrs in the catacombs of Rome, so that when churches were built for public worship, it was natural to place relics of the saints in the altars, in what can also be seen as an echo of Rev. 6.9: ‘I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held’. The practice continues to the present, hence the placing of the relics of St Thomas Aquinas under the main altar in les Jacobins, Toulouse.
Virtually all stone altars were removed from churches in the British Isles in the late 16th century, but at the remote church of Patricio, near Abergavenny, the original nave altars remain in situ, in front of the stunning roodscreen and loft (c.1500).
Altar slabs generally are very plain, bearing just the consecration crosses, symbolizing the Five Wounds of Christ, but the 13th-century altar slab at South Raynham (Norfolk) has characteristic dog-tooth decoration round the edges. Minor altars tended to be no more than six feet long, but the 8′ 6″ mensa at Eccles (Norfolk) was restored to use after the Second World War by S.E. Dykes Bower.
Penetrate to the tiny village of Avenas, in a remote corner of the Bourbonnais, south-west of Mâcon, and you will find the most amazing 12th-century stone altar, bearing on its west face Christ in Glory, surrounded by the Twelve Apostles.