Northburgh Castle, also known as Green Castle or Greencastle Castle, is a 13th/14th-century ruin in Greencastle, Ireland. Completed in 1305 by Richard Óg de Burgh, it controlled Lough Foyle and served expansion plans. Edward Bruce captured it in 1316, and it later became an O'Doherty stronghold. The castle features an oval enclosure with a twin-towered gatehouse and a later large tower. Influenced by Edward I, it symbolized a shift from pure military structures to administrative centers. Damaged by cannon fire, the castle is now managed by the Irish government and accessible from the town and shore.
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.