The city of Oslo has been ageing extremely rapidly in the 20th century, turning 300 years in 1924, before leapfrogging to 900 in 1950 and finally 1000 by the year 2000.
The city succeeded in ageing 100 years in the span of 50 years on the grounds of archaeological findings suggesting that the town had a central administration and was, thus, a town as opposed to a mere cluster of dwellings, 50 years earlier than was previously assumed.
The even more astounding leap from 300 to 900, on the other hand, is a tale of two cities - Christiania and Oslo - and is due to a royal decision that cut the latter from the roots of its medieval past. The new town of Christiana was founded in 1624, leaving the old town of Oslo abandoned to rural pasture.
Whether or not Oslo had developed into a town by the year 1000, as is now believed, or was funded by royal decree only 50 years later, as one written record suggests, it soon become the most influential area of the southeast of Norway. Its population throughout the middle ages was much less than that of the commercial port of Bergen. However, Oslo was still amongst the three original bishoprics of the kingdom.
At the foot of a hill, where the river of Alna flows into the fjord basin, the small town consisted for the most part of thatched log houses in between which were interspersed stone clad churches and monasteries.
Among the few residences constructed in stone were those of the bishop and the king, forming the two most impressive clusters in an otherwise mostly wooden townscape. At the northern end, closely adjacent to the market square was the residence of the bishop, which was linked by a walkway to the Romanesque cathedral of St. Hallvard. The cathedral was begun in the early 1100s and was probably complete by 1130.
Not to be outdone, the king linked his residence to a royal chapel, dedicated to the Virgin Mother, and strove to outshine the cathedral by the erection of a twin towered west front in brick and with elements of contemporary gothic. Oslo also saw the construction of a number of other churches and monasteries.
Oslo, however, had no city wall and the royal residence remained poorly defended at a time when the throne was fiercely contested in a succession of civil wars. The solution was, therefore, to build a more heavily fortified complex across the bay that could bar easy access to Oslo by invaders from sea. This fortress and new royal residence came to be known as Akershus fortress. It is assumed that the complex was begun in the 1290s in the aftermath of the assault on Oslo in 1287.
The fortunes of Oslo grew with the waning of Norwegian maritime influence and the loss of control of islands across the sea. The Oslo area had throughout its history often found itself within a Danish, rather than a Norwegian, orbit, and its possible that a royal presence in the east was warranted by defensive purposes foremost.
In 1314, Oslo laid its definite claim to the title of capital of Norway by way of a royal declaration. The seal of the realm was to be held by the royal Chancellor, a national administrator tied to the royal residence of Oslo.
Over the next 150 years, the influence of Norway, and with it Oslo, dwindled entirely. Swedish nobles rebelled and ultimately fought successfully against the power of Copenhagen while the Norwegians attempted but failed, in a series of events that lead only to the elimination of the Norwegian nobility. Oslo retained certain functions of a capital, though these were increasingly symbolic and by the first half of the 1500s they ceased altogether.
Repeated fires and outbreaks of plagues likewise ensured that that the ex-capital remained economically stagnant. By 1624, Oslo was a backwater with only the cathedral still functioning as a church. A few minor residences in stone had been added to the townscape in the preceding century. One of these were built on top of the remains of the old Bishop’s palace and must have been among the most representative buildings of the time, as it was used for the wedding of James I of Scotland, who later also ruled in England. However, Oslo was still wholly medieval and a shadow of its former self.
It was said to have burnt to the ground at least 14 times, but by 1624, the royal orders from Copenhagen decreed that Oslo should not be rebuilt, at least not in the same place. In the same year, the town of Christiania was founded on the opposite side of the bay and was incorporated into the defensive framework of the royal fortress of Akershus.