Armenelos the Golden, refered to as The City of Kings, was the capital and (in later years) the largest city of Númenor. The name contains the elements Ar(a)- (high, kingly), Menel (heaven), and Os(t) (city, fortress).
It was founded as far back as the end of the First Age, when the Edain first migrated to the island. Conceivably Arandor was the first district they settled after landing in a firth that later led to the haven of Rómenna.
Armenelos contained the royal palace, the King's House, reportedly built with the help of the Maiar. Its finishing, together with the coronation of Elros in 32 S.A. marked the beginning of the Númenorean realm.