States of Austria arable terrain. The other five states, in contrast, are located in the Alps and thus are comparatively unsuitable for agriculture. Their terrain is also relatively unfavourable to heavy industry and long-distance trade. Accordingly, the population of what now is the Republic of Austria has been concentrated in the former four states since prehistoric times. Austria's most densely populated state is the city-state of Vienna, the heart of what is Austria's only metropolitan area. Lower Austria ranks only fourth with regard to population density even though it contains Vienna's suburbs; this is due to large areas of land being predominantly agricultural.
States of Germany are not covered by the normal administrative structure of the respective states. In 2010 only three "Kommunalverbände besonderer Art" exist. Ämter ("offices" or "bureaus"): In some states there is an administrative unit between the districts and the municipalities, called "Ämter" (singular "Amt"), "Amtsgemeinden", "Gemeindeverwaltungsverbände", "Landgemeinden", "Verbandsgemeinden", "Verwaltungsgemeinschaften", or "Kirchspiellandgemeinden". Municipalities ("Gemeinden"): Every rural district and every "Amt" is subdivided into municipalities, while every urban district is a municipality in its own right. There are () 12,141 municipalities, which are the smallest administrative units in Germany. Cities and towns are municipalities as well, also having city rights or town rights ("Stadtrechte").