Fredriksvern (also called Friderichsværn (1801), Frederiksværn (1865), Fredriksværen (1900) and abbreviated Frsværn) was an important Norwegian naval base, just south of Larvik in Vestfold. The town of Stavern has in many ways come to be because of this naval base. Fredriksvern or Stavern has probably been a harbor since ancient times. The name is found in written sources the 11th century and in the 12th century it is referred to as a good fishing harbor. Fredriksvern Church was finished in 1756 as the garrison church in a style with influences from both renaissance and baroque.