Complex sentence: President Richard von Weizsäcker made Schloss Bellevue in Berlin his primary official residence in 1994; since that time the Hammerschmidt Villa has served as a secondary official seat and secondary official residence for the President.
Split into simpler sentences: President Richard von Weizsäcker made Schloss Bellevue in Berlin his primary official residence in 1994. Since 1994, the Hammerschmidt Villa has served as a secondary official seat and secondary official residence for the President.