Church of the Cross was a small medieval parish church for the northern part of the Old Town of Oslo. The ruin was rediscovered in 1922 and is now a part of the Ruin Park containing the ruins of the church and the greater St. Hallvard's Cathedral.
There is no definite information about when the church was built. The church is not mentioned in the sources of the fighting in Oslo in 1240 between King Haakon IV and Duke Skule, suggesting that it is possibly younger. In 1989 it was found a stick with runic inscriptions, dated to the first half of the 1200s. The name Church of the Cross occurs in this inscriptions, and it indicates that it may be older than 1240. When the church was built, it was located far north in the city, and an urban development north of the church came in the second half of the 1200s and the 1300s.
Church of the Cross had input from the west, from the cemetery, an entrance from the west and an entrance directly to the chancel from the south. The remains of the original altar foundation is visible. Around the church are the remains of the cemetery wall.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.