monotheletism
Doctrine developed in the 7th century by Patriarch Sergios, who wanted to reconcile the Orthodox with the monophysites of the Byzantine Empire. Monothelitism supported that Jesus had two natures but only one will. Despite the efforts of Emperor Herakleios (610-641) to impose the new doctrine, monothelitism, was renounced as a heresy in 680.

Sixth Ecumenical Council/ Quinisext/ Dome (Constanitnople, 681/ 691)
The Sixth Ecumenical Counsil (also called: Quinisext<Penthekti or Dome Counsil<in Trullo, mean. in the dome) assembled at Constntinople twice, the years 680/1 (the Sitxth) and 691/2 (the Quinisext/Dome), to discuss the restoration of the association with the Holy See of Rome as well as to clarify practical issues of everyday life for the Cristians.

triumphal arch
(Rom.:) A structure in the shape of a monumental archway, built to celebrate the victory of a Roman general or Emperor.(Byz. Archit.) The arch formed above the Horaia Pyle (Royal Door), which frames the curve of the conch of the apse and separates the bema from the nave.

Tyche (Fortuna)
A symbol of wealth and prosperity, Tyche was considered a deity in the Graeco-roman world (it latin version being Fortuna) and it was often associated with certain cities, as an expression of their power and success. Its iconogrpaphic expression was a personification of the city in the form of a goddess of great importance for this particular city.