Beethoven dedicated several works to the family, such as the Appassionata sonata, Fantasia for Piano Op. 77, Piano Sonata No. 78 in F sharp, sonata Op. 27 No. 2, better known as the ‘Moonlight Sonata’ (it was in fact dedicated to Giulietta Guicciardi, also a member of the family due to her mother, Susanna Brunszvik)

Beethoven's relations with the v. Brunwick family was extensive. The wife of Count Antal v. Brunswick Jr., Baroness Anna Wanckel von Seeberg (1752 - 1830) was a subscriber to the Piano Trio (op. 1) of the young composer in 1795. In 1799 she travelled to Vienna with her two daughters, the 24-year-old Teresa and 21-year-old Josephine to take piano lessons with Beethoven. Then Bethoven became acquainted with Ferenc, their brother, who became his friend and patron for life.

From the outset, Beethoven gave special attention to Josephine. But the younger Brunswick girl married to Count Joseph Deym in 1800. She lived in Vienna most of the time, and Beethoven was a frequent guest in their salon. In 1804, Josephine became widowed with four children then in 1810 she married to the Estonian Baron Kristóf Stackelberg. The news of their marriage made Beethoven mournful.

Brunswick (Bruszvik) Castle also houses the Agroverzum Centre of Science and Fun, the Visitors’ Centre of the Centre for Agricultural Research in Martonvásár. It is an indoor play centre and an educational place at the same time. Its main goal is to show you agricultural sciences in an understandable yet enjoyable way. The Centre for Agricultural Research in Martonvásár maintains the castle's English landscape park.

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