part_of sognsvann 
___MASK84___ . The introduction of self - ___MASK65___ in rural districts was a major political change . The Norwegian farm culture (" bondekultur ") that emerged came to serve as a symbol of nationalistic resistance to the forced union with Sweden . The ___MASK57___ of 1837 gave both the towns and the rural areas the same institutions : a minor change for the town , but a major advance for the rural communities . The significance of this ___MASK57___ is hailed by a nationalistic historian , Ernst Sars : The Sognsvann Line is a rapid transit line on the ___MASK62___ of Norway . It branches from the Common Tunnel at Majorstuen and runs to Sognsvann . After Ullevål stadion , the Ring Line branches off . The Sognsvann Line serves the northwestern and northern neighborhoods of Oslo , mostly within the borough of Nordre Aker . The line is owned and maintained by Kollektivtransportproduksjon and has nine stations . The western end of line 5 serves the entire line . Line 4 and the eastern end of line 5 serve the southern part of the line up to Ullevål stadion before branching off and continuing along the Ring Line . This gives an average five - minute headway on the southern part and an average fifteen - minute headway on the northern part of the line . Headway is a measurement of the minimum possible distance or time between vehicles in a transit ___MASK51___ , without a reduction in the speed of vehicles . The precise definition varies depending on the application , but it is most commonly measured as the distance from the tip of one ___MASK78___ to the tip of the next one behind it , expressed as the time it will take for the trailing ___MASK78___ to cover that distance . A " shorter " headway signifies a more frequent service . Freight trains might have headways measured in parts of an ___MASK52___ , metro systems operate with headways on the order of 1 to 5 minutes , and vehicles on a freeway can have as little as 2 seconds headway between them . The ___MASK62___ ( or or simply ) is the rapid transit system of Oslo , Norway , operated by Sporveien T - banen on contract from the transit authority Ruter . The network consists of five lines that all run through the city centre , with a total length of , serving 101 stations of which 17 are underground or indoors . In addition to serving 14 out of the 15 boroughs of Oslo ( all except St . Hanshaugen ), two lines run to Bærum . In 2015 , the system had an annual ridership of 94 . 4 million . Sognsvann station is the last stop on Sognsvann Line , the western side of line 6 on the Oslo T - bane . The station is located south of the lake Sognsvann . Next to the station on the west side is the ___MASK77___ School of Sport Sciences , while on the east side are the ___MASK77___ National Archives . The station was opened along with the Sognsvann Line on 10 October 1934 . Along the line , it lies 8 . 7 km from Stortinget and at an altitude of 198 . 1 metres . Nordre Aker is a district of the ___MASK88___ of Oslo , Norway . The Common Tunnel , sometimes called the Common Line , is a long tunnel of the ___MASK62___ which runs through the city center of Oslo , Norway . The name derives from the fact that all six lines of the metro use the tunnel , which runs from Majorstuen to Tøyen . The section has six stations , including the four busiest on the metro . Akershus is a county in Norway , bordering Hedmark , Oppland , Buskerud , Oslo , and Østfold ; it also has a short border with Sweden ( Värmland ). Akershus , with more than half a million inhabitants , is the second - largest county by ___MASK53___ after Oslo . The county is named after Akershus ___MASK30___ . The county administration is in Oslo , which is not part of the county " per se ". Akershus ___MASK30___ or Akershus Castle is a medieval castle that was built to protect Oslo , the capital of Norway . It has also been used as a prison . Oslo is the capital and the most populous ___MASK88___ in Norway . It constitutes both a county and a municipality . Founded in the year 1040 , and established as a " kaupstad " or trading place in 1048 by Harald Hardrada , the ___MASK88___ was elevated to a bishopric in 1070 and a capital under Haakon V of Norway around 1300 . Personal unions with Denmark from 1397 to 1523 and again from 1536 to 1814 and with Sweden from 1814 to 1905 reduced its influence . After being destroyed by a fire in 1624 , the ___MASK88___ was moved closer to Akershus Fortress during the reign of Christian IV of Denmark and renamed Christiania in his honour . It was established as a municipality (" formannskapsdistrikt ") on 1 January 1838 . Following a spelling reform , it was known as Kristiania from 1877 to 1925 , at which time its original Norwegian name was restored . Norway (; ___MASK77___ : ( Bokmål ) or ( Nynorsk ); Sami : " Norgga "), officially the Kingdom of Norway , is a sovereign and unitary ___MASK22___ whose territory comprises the western portion of the Scandinavian Peninsula plus the island Jan Mayen and the archipelago of Svalbard . The ___MASK50___ Peter I Island and the sub - ___MASK50___ Bouvet Island are dependent territories and thus not considered part of the Kingdom . Norway also lays claim to a section of Antarctica known as Queen Maud Land . Until 1814 , the Kingdom included the Faroe Islands ( since 1035 ), Greenland ( 1261 ), and Iceland ( 1262 ). It also included Shetland and Orkney until 1468 . It also included ___MASK73___ provinces , now in Sweden : ___MASK66___ , Härjedalen and Bohuslän . A personal union is the combination of two or more states that have the same monarch while their boundaries , laws , and interests remain distinct . It differs from a ___MASK56___ in that each constituent ___MASK81___ has an independent ___MASK65___ , whereas a unitary ___MASK81___ is united by a central ___MASK65___ . The ruler in a personal union does not need to be a hereditary monarch . Sognsvann ( or " Sognsvannet ") is a 3 . 3 km circumference lake just north of Oslo , Norway . Harald Sigurdsson ( Old Norse : " Haraldr Sigurðarson "; ___MASK44___ . 1015  25 September 1066 ), given the epithet Hardrada (" harðráði ", roughly translated as " stern counsel " or " hard ruler ") in the sagas , was King of Norway ( as Harald III ) from 1046 to 1066 . In addition , he unsuccessfully claimed the Danish throne until 1064 and the English throne in 1066 . Prior to becoming king , Harald had spent around fifteen years in exile as a mercenary and military commander in Kievan ___MASK47___ and of the Varangian Guard in the Byzantine ___MASK54___ . Rapid transit , also known as heavy rail , metro , subway , tube , or underground , is a type of high - capacity public ___MASK98___ generally found in urban areas . Unlike buses or trams , rapid transit systems are electric railways that operate on an exclusive right - of - way , which cannot be accessed by pedestrians or other vehicles of any sort , and which is often grade separated in tunnels or on elevated railways . Christian IV ( 12 ___MASK91___ 1577  28 February 1648 ), sometimes colloquially referred to as Christian Firtal in ___MASK11___ and Christian Kvart or Quart in Norway , was king of ___MASK11___ - Norway and Duke of Holstein and Schleswig from 1588 to 1648 . His 59 - year reign is the longest of Danish monarchs , and of Scandinavian monarchies . Haakon ___MASK46___ Magnusson ( 10 ___MASK91___ 1270 - 8 ___MASK58___ 1319 ) ( Old Norse : " Hákon Magnússon "; Norwegian : " Håkon Magnusson ") was king of Norway from 1299 until 1319 . A lake is an area of variable size filled with water , localized in a basin , that is surrounded by land , apart from any ___MASK12___ or other outlet that serves to feed or drain the lake . Lakes lie on land and are not ___MASK68___ of the ___MASK41___ , and therefore are distinct from lagoons , and are also larger and deeper than ponds , though there are no official or scientific definitions . Lakes can be contrasted with rivers or streams , which are usually flowing . Most lakes are fed and drained by rivers and streams .