The purpose of this study is to find more information of the complicated air flow pattern in the Schonbrunn palace. The aim is to improve the control of the air infiltration. We have used a passive tracer gas technique, a special case of the constant injection technique, called the homogeneous emission technique. The results gives Air Change Rate's (ACH) of 0,7 to 1,7 in different rooms and parts of the palace. Wind driven ventilation dominates stack driven ventilation. We found a considerable air flow between floors. Simple one zone calculations of air leakage over windows partly confirms the ACH measured. The palace management will use the results of the investigation in the ongoing planning process to improve the indoor climate and abating the indoor deterioration.