Of the Consecration of Churches

 
From Liturgical Arts Journal:

The tradition of consecrating churches is thought to date back to the first century, and the antiquity of the specific ceremony we are treating today is already attested to already by the time of St. Gregory the Great.

The Catholic Encyclopedia comments:

Before the time of Constantine the consecration of churches was, on account of the persecutions, necessarily private, but after the conversion of that emperor it became a solemn public rite, as appears from Eusebius of Cæsarea (Church History X): "After these things a spectacle earnestly prayed for and much desired by us all appeared, viz. the solemnization of the festival of the dedication of churches throughout every city, and the consecration of newly-built oratories." The passage clearly indicates that churches were consecrated before, and that accordingly the anniversaries of the dedication might now be publicly celebrated.

Of course, what the precise form of this consecration was is not entirely clear, but "we find occasional notices of the vigil kept before the consecration, of the translation of the relics, and of the tracing of the Greek and the Latin alphabet on the pavement of the church... Often only the Greek alphabet or the Latin was written twice; and sometimes to the Greek and Latin the Hebrew alphabet was added (Martène, De Antiquis Ecclesiæ Ritibus, II)." (Source: Catholic Encyclopedia)

In short, there was some variety in this regard, but also a remarkable unity and continuity that was preserved down the ages.

The particular form of this ceremony sees some other minor variations as well, at least in the modern age. In some instances a smaller cross is laid out before the sanctuary in the nave as follows: (Read more.)