Question: In which country is the Staverns Fortress located in the county of Vestfold?

Context paragraphs:
Bergenhus Fortress: Bergenhus fortress (Norwegian: "Bergenhus festning" ) is a fortress located in Bergen, Norway.  Bergenhus fortress is located in the entrance to the harbour in Bergen.  It is one of the oldest and best preserved castles in Norway.

Staverns Fortress: Staverns Fortress was a military facility located on the island of Citadelløya at Stavern in Vestfold, Norway.

Vestfold: Vestfold ] is a county in Norway, bordering Buskerud and Telemark.  The county administration is in Tønsberg, and the largest city is Sandefjord.  With the exception of Oslo county, Vestfold is the smallest county in Norway by area.

Bjni Fortress: Bjni Fortress (Armenian: Բջնի Բերդ ), is a medieval Armenian fortress located in the village of Bjni in the Kotayk Province of Armenia.  It sits upon the top and along the sides of a mesa that divides the village nearly in half.  The larger portion of which is located west of the mesa and curves south, while a smaller portion is east.  The walls of the fortress may only be seen from the western side of the village, and are easiest reached via a narrow dirt road that forks (take the left fork) and goes up the side of the hill past some residences.  Bjni Fortress is 1504 m above sea level.

Aberystwyth Castle: Aberystwyth Castle (Welsh: "Castell Aberystwyth" ) is a Grade I listed Edwardian fortress located in Aberystwyth, Ceredigion, Mid Wales.  It was built in response to the First Welsh War in the late 13th century, replacing an earlier fortress located a mile to the south.  During a national uprising by Owain Glyndŵr, the Welsh captured the castle in 1404, but it was recaptured by the English four years later.  In 1637 it became a Royal mint by Charles I, and produced silver shillings.  The castle was slighted by Oliver Cromwell in 1649.

Tuancheng Fortress: The Tuancheng Fortress or Tuan Cheng Fortress (Chinese:  團城演武廳 ,  团城演武厅 ,  "Tuánchéng Yǎnwǔtīng",  "Round Wall Fortress") is a historic 18th-century fortress located near the Fragrant Hills in the Haidian District of Beijing, China.  Today, the fortress is a national museum and is also known as the Tuancheng Exhibition Hall.

Skopje Fortress: The Skopje Fortress (Macedonian: Скопско Кале , transliterated "Skopsko Kale"), commonly referred to as Kale (from "kale", the Turkish word for 'fortress'), is a historic fortress located in the old town of Skopje, the capital of the Republic of Macedonia.  It is situated on the highest point in the city overlooking the Vardar River.  The fortress is depicted on the coat of arms of Skopje, which in turn is incorporated in the city's flag.

Ushiberd: Ushiberd (Armenian: Ուշիբերդ ) is an Iron Age fortress located upon a hill just outside the village of Ushi in the Aragatsotn Province of Armenia.  It has almost completely collapsed except for portions of the walls that once surrounded the fortress, located around the edge of the hill before it descends.  Within the area that was once the interior of the fortress are large piles of large stones that once made up the fortification walls and structures within.  Just below the hill is Saint Sargis Monastery of the 7th–13th centuries.  It sits at the far side of what was once a settlement site from the 3rd–1st millennia BC.  Nearby, down the main road that leads back into Ushi from the monastery and fortress, is a small chapel from the 10th century.

Vaberget Fortress: Vaberget Fortress (Swedish: "Vabergets fästning" ) is a fortress located five kilometers west of Karlsborg Fortress, by lake Vättern, in Västergötland, Sweden.  The southern fort at Vaberget Fortress was the first fort in the world that fully used the protection provided by the bedrock itself by having all of its functions embedded in the mountain.

Vestfold University College: Vestfold University College (Norwegian: "Høgskolen i Vestfold" , abbreviated as HiVe) was a university college in the county of Vestfold, Norway.  The university college's campuses were formerly located in Borre and Eik.  From 2010 the whole university college was co-located at Campus Bakkenteigen in Horten.  It was established 1 August 1994 by the merger of three previous university colleges, and has approximately 4000 students and 450 employees.  The university college has four faculties: Humanities and Education, Health Sciences, Business and Social Sciences, and Technology and Maritime Sciences.  The college merged with Buskerud University College on 1 January 2014 to create Buskerud and Vestfold University College.

Supporting paragraphs: Staverns Fortress Vestfold
Answer: Norway