Consecration crosses mark the points on the wall where a church was anointed when it was consecrated by the Bishop. The ritual of consecration is intended to sanctify the building and dedicate it to God. It therefore separates it from the ‘ordinary’ space outside, and differentiates it from other buildings.
The consecrating bishop makes twelve signs of the cross, three on each wall. Each is marked with holy oil and a candle placed under it.