Tienen or Thienen (French: Tirlemont) is a city an municipality in the province of Flemish Brabant, in Flanders, one of the three regions of Belgium. The municipality comprises the city of Tienen proper and the towns of Bost, Goetsenhoven, Hakendover, Kumtich, Oorbeek, Oplinter, Sint-Margriete-Houtem and Vissenaken. On January 1, 2006 Tienen had a total population of 31,835. The total area is 71.77 km² which gives a population density of 444 inhabitants per km².