This research thesis focuses on the religious architecture in Agia during the post-Byzantine era.

Agia is a town of 3.169 inhabitants, located south foot of mount Ossa (also known as Kissavos), 35 km east of Larissa.

The area around Agia is considered to be of historical and archaeological value as, according to researchers, a religious community was formed and several churches, monasteries and hermitages were built. This community is thought to have been active until the 14^th century.

Throughout Agia lay fourteen temples built between the 12^th and the 19^th century, most of which have an elongated rectangular shape. Some of them are of particular architectural interest, whilst others host remarkable murals and interior decorations. Naturally, none of the aforementioned temples maintained its original form.

Out of these temples, seven can be distinguished because of their form; they are three-aisled Basilicas. This research thesis attempts to thoroughly study these seven temples, some of them for the first time ever. The drawings (plans and elevations) and the photographs accompany the descriptions about the building techniques and the morphology of the temples. The historical period during which the temples were built, is vital to this study of the three-aisled Basilicas in Agia in order to compare them and reach conclusions about the religious architecture of that era as well as the development of Agia which still preserves its historical and cultural importance.