Castle Arenberg is built on the exact spot where there was once a 12th century water castle. Antoon Van Croy demolished that old castle except for one tower and replaced it by the current castle, which was finished in 1515. His grandson was responsible for the beautiful park around the castle. There were some minor alterations done throughout the centuries but the castle kept pretty much it original looks. The first theatre of Belgium was founded in the castle in 1616. Voltaire was often a guest in the castle. On November 21st, 1783 Professor Jan-Pieter Minckelerís took off for the first time in history with a gas filled balloon from the front lawn of the castle. The castle is now property of the University of Leuven. You can walk freely in the park and through the gate into the courtyard of the castle. Close to the castle are a couple of taverns where you can get some yummy ice cream :). Castle Arenberg is in Heverlee very close to Leuven.