The Holy Trinity Church has a cross shaped plan with a dome. It is composed of the nave, narthex (entrance area) and the altar alcove. In the church many Byzantine architecture features have been skilfully used such as the inner organization of the space and the decorative and illuminative systems. These features, together with the pyramidal shape, forms and proportions give the church a picturesque appearance. The Byzantine architectural elements in the church have been combined with western architectural elements belonging to the same period.
Inside the church are two columns with reused capitals (thought to have been taken from classical ruins in the city). An inscription inside the church contains the name of Andronicus Paleologus (Governor of the province of Berat from 1302 to 1326), indicating that the church must have been built during the 13th or 14th century with his financial support.References:
The eight towns in south-eastern Sicily, including Ragusa, were all rebuilt after 1693 on or beside towns existing at the time of the earthquake which took place in that year. They represent a considerable collective undertaking, successfully carried out at a high level of architectural and artistic achievement. Keeping within the late Baroque style of the day, they also depict distinctive innovations in town planning and urban building. Together with seven other cities in the Val di Noto, it is part of a UNESCO World Heritage Site.
In 1693 Ragusa was devastated by a huge earthquake, which killed some 5,000 inhabitants. Following this catastrophe the city was largely rebuilt, and many Baroque buildings from this time remain in the city. Most of the population moved to a new settlement in the former district of Patro, calling this new municipality 'Ragusa Superiore' (Upper Ragusa) and the ancient city 'Ragusa Inferiore' (Lower Ragusa). The two cities remained separated until 1926, when they were fused together to become a provincial capital in 1927.