Tønsberg [²tønsbær] (listen) is a municipality in Vestfold county, southern Norway, located around 102 kilometres (63 miles) south-southwest of Oslo on the western coast of the Oslofjord near its mouth onto the Skagerrak. The administrative centre of the municipality is the town of Tønsberg. The municipality has a population of 41,239 and covers an area of 107 square kilometres (41 square miles).

Tønsberg is generally regarded as the oldest town in Norway. Tønsberg was established as a municipality on 1 January 1838 (see formannskapsdistrikt). The rural municipality of Sem was merged into the municipality of Tønsberg on 1 January 1988.

The Old Norse form of the name was Túnsberg. The first element is the genitive case of tún (n), meaning fenced area or garden. The last element is berg (n), meaning mountain. The name originally referred to the fortifications on Slottsfjellet. The old spelling has been retained in the name of the diocese, Tunsberg bispedømme.

The coat of arms is an old city seal from as far back as 1349. The seal shows Tønsberg Fortress surrounded by a ring wall on a mountain with the sea in front. There is also a longship in the water in front of the fortress. Around the seal are the words (in Latin): This is the seal of Tunsberg.

...
Wikipedia