Complex sentence: The capital of Lower Austria since 1986 is Sankt Pölten (most recent capital town in Austria), but formerly, the capital of Lower Austria was Vienna, even though Vienna is not properly part of Lower Austria.
Split into simpler sentences: The capital of Lower Austria (since 1986) is Sankt Pölten--the most recent capital town in Austria. Prior to 1986, the capital of Lower Austria was Vienna, even though Vienna is not properly part of Lower Austria.