Catacombs of Commodilla, on the Via Ostiensis, contain one of the earliest images of a bearded Christ. They originally held the relics of Saints Felix and Adauctus. The hypogeum leading to the catacombs was built in the fourth century. The catacombs were used for burials until the sixth century. Later, as happened to other Christian underground cemeteries, it was transformed into a place of worship of martyrdom: restoration of the basilica underground were made by several popes until the ninth century, a sign that the catacombs were still at that time a place of pilgrimage of devout Christians.
There were also found coins bearing the effigy of Pope Gregory IV (827-844) Pope Leo IV (847-855) finally gave the relics of the martyrs Felix and Adautto the wife of Emperor Lothair. Following the catacombs were abandoned and fell into oblivion. It was discovered in 1595 by archaeologist Antonio Bosio, but the first to identify it as that of Commodilla was in the nineteenth century, Giovanni Battista de Rossi. Restoration campaigns were performed at the beginning of the twentieth century and led to the complete excavation of the second level cemetery.
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.