Short answers, pulled from the story.
The Venus of Willendorf, a 28,000-year-old limestone figurine found in Austria, proves that human life existed in the area during the Paleolithic period. The city of Hallstatt holds the oldest archaeological evidence of Celts anywhere in Europe dating back to the 6th century BC.
Rudolph I of Germany defeated Ottokar II at Dürnkrut in 1278 and began Habsburg rule over Austria. The Habsburgs accumulated provinces throughout the 14th and 15th centuries including most of the Netherlands through Maximilian's marriage to Maria of Burgundy in 1477 and Spain after Philip the Fair wed Joanna the Mad in 1496.
Gavrilo Princip assassinated Archduke Franz Ferdinand in Sarajevo on the 28th of June 1914. This event triggered World War I and led to the eventual dissolution of Austria-Hungary with over one million Austro-Hungarian soldiers dying during the conflict.
Austria declares permanent neutrality through parliamentary act on the 26th of October 1955 which now marks Austria's National Day public holiday. All occupation troops left by this date following the Austrian State Treaty that ended Allied occupation on the 15th of May 1955.
Forest cover reached 47% of the total land area in 2020 equivalent to 3,899,150 hectares. Naturally regenerating forest covered 2,227,500 hectares while planted forests accounted for 1,671,500 hectares according to geographic surveys.
A referendum gave two-thirds majority consent for EU membership effective the 1st of January 1995. A separate referendum in 1978 voted approximately 50.5% against nuclear power despite a finished plant at Zwentendorf leading Parliament to pass laws forbidding electricity generation from nuclear sources.