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:Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.