query: part_of sognsvann 
supports: 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 population after Oslo. The county is named after Akershus Fortress. The county administration is in Oslo, which is not part of the county "per se". 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 federation in that each constituent state has an independent government, whereas a unitary state is united by a central government. The ruler in a personal union does not need to be a hereditary monarch. The Common Tunnel, sometimes called the Common Line, is a long tunnel of the Oslo Metro 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. The Sognsvann Line is a rapid transit line on the Oslo Metro 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. Nordre Aker is a district of the city of Oslo, Norway. Norway (; Norwegian: (Bokmål) or (Nynorsk); Sami: "Norgga"), officially the Kingdom of Norway, is a sovereign and unitary monarchy whose territory comprises the western portion of the Scandinavian Peninsula plus the island Jan Mayen and the archipelago of Svalbard. The Antarctic Peter I Island and the sub-Antarctic 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 the following provinces, now in Sweden: Jämtland, Härjedalen and Bohuslän. Rapid transit, also known as heavy rail, metro, subway, tube, or underground, is a type of high-capacity public transport 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. 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 Norwegian School of Sport Sciences , while on the east side are the Norwegian 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 . Sognsvann (or "Sognsvannet") is a 3.3 km circumference lake just north of Oslo, Norway. Oslo is the capital and the most populous city 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 city 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 city 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. Christian IV (12 April 1577  28 February 1648), sometimes colloquially referred to as Christian Firtal in Denmark and Christian Kvart or Quart in Norway, was king of Denmark-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. Harald Sigurdsson (Old Norse: "Haraldr Sigurðarson"; c. 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 Rus' and of the Varangian Guard in the Byzantine Empire. Headway is a measurement of the minimum possible distance or time between vehicles in a transit system, 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 vehicle to the tip of the next one behind it, expressed as the time it will take for the trailing vehicle to cover that distance. A "shorter" headway signifies a more frequent service. Freight trains might have headways measured in parts of an hour, 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. Haakon V Magnusson (10 April 1270 - 8 May 1319) (Old Norse: "Hákon Magnússon"; Norwegian: "Håkon Magnusson") was king of Norway from 1299 until 1319. The Oslo Metro (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. A lake is an area of variable size filled with water, localized in a basin, that is surrounded by land, apart from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, 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. Akershus Fortress 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. History.
  The introduction of self-government 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 legislation 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 legislation is hailed by a nationalistic historian, Ernst Sars:
candidates: 25 antarctic april c castle city denmark english farm federation fortress government history hour härjedalen iii jämtland legislation minute municipality norwegian order oslo metro part population river rus ' state system transport v vehicle year
answer: oslo metro