Djuma Mosque is the oldest mosque in Derbent and one of the oldest in Russia. It was built over a 6th-century Christian basilica around 733-734 AD. It has a 15th-century madrassa.
There are three naves in the inside of the mosque. The width of central nave is 6.3 m, side naves are 4 m wide. The naves are separated by square columns 97 to 97 cm wide, that have profiled capitals. The columns are connected by lancet arches.
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.