Caerleon is the historically important site of the Roman legionary fortress of Isca Augusta. St Cadoc's Church stands over the principia (headquarters), where the legionary standards were kept and statues of the Roman emperors venerated. The earliest surviving part of the church dates back to just after the kingdom of Glywysing was overrun by the Normans during the twelfth century and is thought to be the work of Hywel ap Iowerth, who was also the founder of the Cistercian Llantarnam Abbey.
The current church is in the Perpendicular style, which was fashionable in the fifteenth century. The tower, which stands at the southwest corner of the church, has a lower stage that was probably part of the original Norman church, incorporating twelfth/thirteenth century lancet windows. The church features a series of impressive stained-glass windows depicting the life of Christ and symbolising the faith and devotion of the saints associated with Caerleon.
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.