The Church of St Martin was begun in the 12th century, although most of the current structure dates from the 13th century. The church is most notable for its extreme tilt, caused as a result of a landslide. This has led to many attempts to strengthen the church and prevent its collapse, through the use of massive tie beams and buttresses.
The church is in the Gothic style, and has a chancel, nave, south porch, and western tower. A round-headed north window dates to the 12th century, and the nave roof has been dated to the late 13th or early 14th century.
In the nave of the church stands a stone cross, sometimes referred to as a wayside cross or crucifix, dated to the 11th or 12th century. In the Middle Ages the cross, which bears a rare carving of Christ on the cross, would have stood in the churchyard to be venerated by pilgrims travelling through the Black Mountains, via Llanthony Abbey, to St David's Cathedral in Pembrokeshire.
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.