The city was once the capital of Arnor, on the shores of Lake Evendim in the north of Eriador. The city was founded by Elendil near where the lake gives rise to the Baranduin (Brandywine) River. The city survived for nearly a thousand years. In the early days of Arnor, it was one of the glories of Middle-earth. Soon after its founding, though, the numbers of the Dunedain of the North began to dwindle. The population of Annúminas seems to have fallen throughout its history, until it was deserted and the kings removed to Fornost to the east.
At the time of the War of the Ring at the end of the Third Age, Annúminas had lain in ruins for more than 2,000 years. There are hints, however, that Aragorn refounded the city and may even have made it his capital early in the Fourth Age.