The origins of Praha or Prague, located on the River Vltava or Moldau, date back to the 9th century, when a Castle was constructed. During the mid 14th century Prague became the capital of the Holy Roman Empire under Emperor Charles IV, also King of Bohemia, and the city became one of the largest in Europe. In 1784 the four independent urban areas Stare Mesto (Old Town, 13th century), Mala Strana (Lesser Town, 13th century), Nove Mesto (New Town, 14th century) and Hradcany (Castle Area, 14th century) were united into one city.