According to our Holy Orthodox Tradition behind and around the Altar we paint icons depicting Holy Hierarchs, Bishops of the Church, who are in a symbolic way concelebrating with the celebrant clergyman the Divine Liturgy.
There are obviously many Hierarch Saints in the Orthodox Church. Choosing the ones that would fit in our own Church is an interesting task.
We usually select the Three Holy Hierarchs and Ecumenical Teachers, St. John Chrysostom, St. Basil the Great and St. Gregory the Theologian.
Then we may choose some more that we are particularly related to, for various reasons. In our Church apart from the Three Great Hierarchs, we have chosen St. Nicholas, St. Spyridon and St. Peter Bishop of Argos.