Complex sentence: The castle is surrounded by vast park that was founded already in 1789 according to the plan of famous Viennese botanist Nikolaus Joseph von Jacquin (1727--1817), it was completed thirteen years earlier than the castle itself.
Split into simpler sentences: The castle is surrounded by a vast park that was founded already in 1789, according to the plan of famous Viennese botanist Nikolaus Joseph von Jacquin (1727--1817). It was completed thirteen years earlier than the castle itself.