Austria is a spectacularly beautiful country at the heart of Western Europe; its location along strategic trade routes of the River Danube have only increased its strategic importance throughout modern history. Austria was once the center of power for the great Austro-Hungarian Empire, whose Hansberg dynasty dominated Europe for centuries . Austria became a small republic after its defeat in World War I, was annexed by Nazi Germany in 1938, and occupied by the victorious Allies in 1945. The actual status of Austria remained unclear for about a decade. A State Treaty signed in 1955 ended the occupation, recognized Austria's independence and sovereignty, but expressly prevented the country from being unifed with Germany. A constitutional law was passed that same year  and declared the country "perpetual neutrality" as a condition for Soviet military withdrawal. That being said, the collapse of the Soviet Union in 1991, and Austria's entry into the European Union in 1995, have together altered the meaning of this permanent neutrality. Today, Austria is a prosperous, democratic country with strong ties to the Western Europe. Austria entered the European Union's Economic and Monetary Union in 1999.