The so-called "Athonite" type of church and two Shrines of the Theotokos in Constantinople

The textual descriptions of alterations carried in the two most important Theotokos’ churches in Constantinople, the Blachernae and the Theotokos in Chalkoprateia, focus on the addition of lateral apses to the buildings. This type is very likely the source of influence and also the basis for the transference of the concept of lateral apses in Athonite katholika