Like an axis in the centre of Karpenissi, the Agia Triada Cathedral, stands there since the second half of the 16th century and is a listed historical monument. It is a great work of Eugenios Giannoulis the Aetolian who, among the other great works he did for the area, utilised the small church that existed there till then giving it its current form, in response to the need of the faithful. In this way, a larger church was built, indeed according to the standards of the basilicas of Constantinople.
Visitors come across the relief inscription above the main gate of the church, which writes:
"ΘΕΑΡΧΙΚΗ ΤΡΙΑΔΙ ΗΣ ΘΡΟΝΟΣ ΠΟΛΟΣ ΚΑΝ ΓΗ ΝΑΟΝ ΤΕΤΕΥΧΕ ΠΙΣΤΩΝ Η ΠΟΛΙΣ ΠΑΣ ΠΙΣΤΟΣ ΕΙΣ ΟΝ ΕΙΣΙΩΝ ΠΟΛΛΩ ΔΕΕΙ ΤΟ ΠΝΕΥΜΑ ΑΣΤΡΑΦΘΗΤΙ ΤΡΙΣΙΝ ΗΛΙΟΙΣ ΤΗΣ ΤΡΙΣΣΟΦΑΟΥΣ ΚΑΙ ΜΙΑΣ ΘΕΑΡΧΙΑΣ"
“ DEDICATED TO THE TRINITY OF GOD WHO HAS HEAVEN FOR ITS THRONE, ALTHOUGH THE CITY OF FAITHFUL HAS BUILT A CHURCH ON EARTH. MAY ALL FAITHFUL ENTERING THIS CHURCH IN AWE BE ENLIGHTENED BY THE THREE SUNS OF THE LIGHT OF TRINITY AND GOD ALMIGHTY”
Over time, dark days have come for the history of the church, which was severely damaged by the Turks. It was destroyed in 1684 and was repaired in 1693 by Lymperakis Gerakaris. It was then completely destroyed in 1756, in a attack known in history as the “Destruction of Karpenissi”, which also accounted for the loss of its extensive library. Subsequently, in 1821 it experienced the wrath of the Turks as it was set on fire along with the other churches of the town. It took its current form in 1960 and since then stands tall, welcoming the faithful and celebrating on the feast day of the Holy Spirit.