Esterion (Elw: enu Esterion; in the Storish language known as Esthersbýur) is a city in north-east Batavia. It was founded in 1624 by King Noah of Elwynn as an Elwynnese city and bailiwick and royal city. It is named after the Elwynnese–Hurmu noblewoman Esther Ayreon-Kalirion, the mother of King Noah.
Belonged to Shirerithian Elwynn 1624–1651, Shireroth's Imperial Dominion of Absentia 1651–1671, the Kingdom of Amokolia (West Amokolia), 1671–1678, Francia 1678–1684, Franco-Batavian Empire 1684–1685, Elwynnese Amokolia 1685–1691, and Batavia from 1691 and onwards (following the implementation of the Treaty of Frijfort).
Esterion is the cathedral city of the Diocese of Esterion (Church of Elwynn (Archdiocese of Yaanek)), established in 1624. The cathedral was consecrated in 1627. It is one of four dioceses of the Archdiocese of Yaanek in Batavia (along with Krieksburgh, Portus Batavii, and Vinandy, and switched allegiance from the Church of Elwynn's archdiocese of Eliria to Yaanek as a result of the Schism of 1699.