The castle is in Troissereux, roughly 5 kilometres north of Beauvais (less than one hour from Paris. To reach the place :

By car :

From Calais or Paris, leave the A16 at the Beauvais Nord way-out. From Senlis, take the dual carriage way towards Beauvais, via Creil and Clermont.

Once reached Beauvais, follow the « Eu, le Tréport » sign.  In Troissereux (7 kilometres), turn left at the traffic light, castle is 500 metres further and you'll leave your car on the side of the road outside the castle.

By train :

Take the train to Beauvais and the cab towards the castle (10 minutes, roughly).