Jamestown is the capital city of the British Overseas Territory of Saint Helena, Ascension and Tristan da Cunha, located on the island of Saint Helena in the South Atlantic Ocean. It is also the historic main settlement of the island and is on its north-western coast. Before the development of the port at Rupert's Bay, it was the island's only port and the centre of the island's road and communications network. It was founded when colonists from the English East India Company settled on the island in 1659 and was briefly occupied by the Dutch East India Company in 1673 before being recaptured. Many of the buildings built by the East India Company in the 18th century survive and give the town its distinctive Georgian flavour.

The British Overseas Territories (BOTs) are the 14 territories with a constitutional and historical link with the United Kingdom that, while not forming part of the United Kingdom itself, are part of its sovereign territory. The permanently inhabited territories are delegated varying degrees of internal self-governance, with the United Kingdom retaining responsibility for defence, foreign relations and internal security, and ultimate responsibility for good governance. All of the territories are inhabited by civilians, except three that are chiefly or only inhabited by military or scientific personnel. All fourteen have the British monarch as head of state. These UK government responsibilities are assigned to various departments of the Foreign, Commonwealth and Development Office and are subject to change.