The southern wing of the Palace complex – which Antal Grassalkovich I rendered at the disposal of his friend, Count Kristóf Migazzi, Bishop of Vác and Cardinal Archbishop of Vienna – was converted into a theatre by Prince Antal Grassalkovich II between 1782 and 1785. Thus the Palace Theatre is the oldest operating stone theatre in Hungary. The baroque theatre, which has seating facilities for 100 guests, operated on a temporary basis, and performances were held only when the prince’s court was in residence in Gödöllö.
Music was supplied by the permanent 24 member orchestra of the Prince. The internal walls are decorated with decorative, classical late baroque wall painting, enlarging the space perspectively. The Castle Theatre was closed down in the year of the Austrian-Hungarian compromise in 1867 during the works, when, with the instalment of two ceilings, the hall was converted into 15 rooms. The Theatre with side-wings, which is unique in Hungary and considered very rare in Europe was excavated in the autumn of 1986.
The reconstruction of the Castle Theatre is a nice example of the construction national heritage, which received the first prize of the FIABCI (International Real Estate Federation) 6th Hungarian Real Estate Development Grand Prix Competition. In May 2004 an award was also received at the international competition in Houston.