Simplify the following text for a Grade 7 native English-speaking person.
Original: From 2004 until early 2006 , Charlottenburg Palace was the seat of the President of Germany , whilst Schloss Bellevue was being renovated .
Simplified: From 2004 until early 2006 , Charlottenburg Palace was the seat of the President of Germany . This was because Schloss Bellevue has been rrenovated .