The lands of Mugdock were a property of the Grahams from the mid-13th century, when David de Graham of Dundaff acquired them from the Earl of Lennox. It is possible that the castle was built by his descendant, Sir David de Graham (d. 1376), or by his son in 1372. In 1458, the lands were erected into the Barony of Mugdock. Later, in 1505, the Grahams were created Earls of Montrose.
The original castle may have been shield-shaped on plan, comprising towers arranged around a courtyard, and linked by curtain walls and ranges of buildings. The castle stood on a natural, steep-sided mound formed of hard volcanic rock. Of the early castle, only the south-west tower remains complete, and forms the most recognisable feature of the ruins. The narrow tower is of four storeys, with an entrance on the first floor, accessed via exterior steps on the east side. Inside the basement is vaulted, and a single room occupies each storey. On the outside, a line of corbels projects the two upper storeys out from the lower levels, giving the tower a distinctive 'top-heavy' appearance. The only other remains are the basement of the north-west tower, part of the gatehouse, and linking sections of curtain wall.
The castle was extended in the mid-15th century, probably around the time that the barony was created. An outer wall was built to enclose the majority of the mound as an outer courtyard. This courtyard had its main entrance to the south, adjacent to the south-west tower. Inside the courtyard are the ruins of various stone buildings, mainly dating from the 16th century. These include a chapel at the north extent of the courtyard, and a domestic range at the south-west. Much of the outer curtain wall has also disappeared, although the southern section remains.
A terraced walled garden, incorporating a summer house, was built to the east of the castle in the 1820s. Local historian John Guthrie Smith (1834–1894), a relative of the Smith family of nearby Craigend Castle, leased the house from 1874. He had the 17th-century mansion demolished, and commissioned a Scottish baronial style house to be built in the ruins of the old castle. It was designed by architects Cambell Douglas & Sellars, and was extended to designs by James Sellars in the 1880s.
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.