Vilnius (Polish: Wilno, Yiddish: ווילנע/Vilne), is the largest city and the capital of Lithuania, with a population of 555,613 (847,954 together with Vilnius County) as of 2008. It is the seat of the Vilnius city municipality and of the Vilnius district municipality. It is also the capital of Vilnius County. Historian Romas Batūra identifies the city with Voruta, one of the castles of Mindaugas, crowned in 1253 as King of Lithuania. The city was first mentioned in written sources in 1323, when the Letters of Grand Duke Gediminas were sent to German cities inviting Germans and members of the Jewish community to settle in the capital city, as well as to Pope John XXII. These letters contain the first unambiguous reference to Vilnius as the capital; Old Trakai Castle had been the earlier base for the Grand Duchy of Lithuania. According to legend, Gediminas dreamt of an iron wolf howling on a hilltop and consulted a pagan priest for its interpretation. He was told: "What is destined for the ruler and the State of Lithuania, is thus: the Iron Wolf represents a castle and a city which will be established by you on this site. This city will be the capital of the Lithuanian lands and the dwelling of their rulers, and the glory of their deeds shall echo throughout the world". The location offered practical advantages: it lay within the Lithuanian heartland at the confluence of two navigable rivers, surrounded by forests and wetlands that were difficult to penetrate. The duchy had been subject to intrusions by the Teutonic Knights.