St. Hallvard's Cathedral (Hallvardskatedralen), the former Oslo Cathedral, was the earliest cathedral in Oslo. The cathedral was built at the height of the Old Town market square Oslo during the early 12th century, and was used as a church until about 1655. Besides being the bishop's seat and religious center of eastern Norway for about 500 years, the cathedral was the coronation church, royal wedding church, chapel royal, and one of Scandinavia's most visited place of pilgrimage. St. Hallvard cemetery is located mainly south of the cathedral. It was the honorary cemetery in Oslo and eastern Norway from around 1130 to 1639. Here the bishops, chiefs and other prominent men and women were buried. The most prominent was interred in the church along with the kings.
Today the cathedral is in ruins. The main body in the ruins park (Memorial Park), the southern part under a concrete cap - and the concrete lid of the street of Bispegata. Towards the end of the 19th century were Bispegata extended in an easterly direction, over the cathedral site. It has been put in place to remove Bispegata's eastern part, as a result of the completion of the Ekeberg Tunnel and the modified veian resort in the lower Lodalen. In that case, the ruins of St. Hallvard Cemetery exposed, and the Medieval city triangular marketplace, Oslo squares, re-established west of St. Hallvard Cemetery. Neighboring the Cathedral was the smaller Church of the Cross.
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.